23 Anaesthesia and pain relief

Chronic pain
Chronic pain
Chronic pain is defined as pain that persists or recurs for more than 3 months. In chronic pain syndromes, pain can be the sole or a leading complaint and requires special treatment and care. This could be ‘chronic primary pain’, which may be conceived of  as a disease in its own right, for example in condi tions such as fibromyalgia or non-specific low-back pain. In six other subgroups, pain is secondary to an underlying disease: chronic cancer-related pain, chronic neuropa thic pain, chronic secondary visceral pain, chronic post-traumatic and postsurgi cal pain, chronic secondary headache and orofacial pain and chronic secondary musculoskeletal pain. These conditions are summarised as ‘chronic secondary pain’, in which pain may at least initially be conceived as a symptom. In sur gical practice, patients with chronic pain may present for treatment of  the cause (e.g. pancreatitis, malignancy) or concomitant benign pathology . Almost 50 years ago, using gate theor y , Melzeck and Wall proposed pain to be not only subjec tive but also a multidimensional experience that incorporates sensory/discriminative, motivational/a ff ect and cognitive aspects. Recent guidance from the International Association for the Study of  Pain highlights tha t the multidimensional aspect is one of  the key components, hence the treatment of  chronic pain involves a multidisciplinary multimodal approach. Mechanistically , chronic pain may be classified into: /uni25CF Nociceptive pain , which may result from musculoskel etal disorders or cancer activating cutaneous nociceptors (pain receptors). Prolonged ischaemic or inflammatory processes result in sensitisation of  peripheral nociceptor and altered activity in the central nervous system, leading to exaggerated responses in the dorsal horn of  the spinal cord. The widened area of  hyperalgesia and increased sen sitivity (allodynia) have been attributed to increased trans mission in the central nervous system. the peripheral or central nerves (excluding the ‘physiolog - ical’ pain due to noxious stimulation of the nerve termi - nals). It is classically of  a ‘burning’, ‘shooting’ or ‘stabbing’ type and may be associated with allodynia, numbness and diminished thermal sensation. It is poorly responsive to - opioids. Examples include trigeminal neuralgia, posther - petic neuropathy and diabetic neuropathy . - Chronic pain
Chronic pain is defined as pain that persists or recurs for more than 3 months. In chronic pain syndromes, pain can be the sole or a leading complaint and requires special treatment and care. This could be ‘chronic primary pain’, which may be conceived of  as a disease in its own right, for example in condi tions such as fibromyalgia or non-specific low-back pain. In six other subgroups, pain is secondary to an underlying disease: chronic cancer-related pain, chronic neuropa thic pain, chronic secondary visceral pain, chronic post-traumatic and postsurgi cal pain, chronic secondary headache and orofacial pain and chronic secondary musculoskeletal pain. These conditions are summarised as ‘chronic secondary pain’, in which pain may at least initially be conceived as a symptom. In sur gical practice, patients with chronic pain may present for treatment of  the cause (e.g. pancreatitis, malignancy) or concomitant benign pathology . Almost 50 years ago, using gate theor y , Melzeck and Wall proposed pain to be not only subjec tive but also a multidimensional experience that incorporates sensory/discriminative, motivational/a ff ect and cognitive aspects. Recent guidance from the International Association for the Study of  Pain highlights tha t the multidimensional aspect is one of  the key components, hence the treatment of  chronic pain involves a multidisciplinary multimodal approach. Mechanistically , chronic pain may be classified into: /uni25CF Nociceptive pain , which may result from musculoskel etal disorders or cancer activating cutaneous nociceptors (pain receptors). Prolonged ischaemic or inflammatory processes result in sensitisation of  peripheral nociceptor and altered activity in the central nervous system, leading to exaggerated responses in the dorsal horn of  the spinal cord. The widened area of  hyperalgesia and increased sen sitivity (allodynia) have been attributed to increased trans mission in the central nervous system. the peripheral or central nerves (excluding the ‘physiolog - ical’ pain due to noxious stimulation of the nerve termi - nals). It is classically of  a ‘burning’, ‘shooting’ or ‘stabbing’ type and may be associated with allodynia, numbness and diminished thermal sensation. It is poorly responsive to - opioids. Examples include trigeminal neuralgia, posther - petic neuropathy and diabetic neuropathy . - Chronic pain
Chronic pain is defined as pain that persists or recurs for more than 3 months. In chronic pain syndromes, pain can be the sole or a leading complaint and requires special treatment and care. This could be ‘chronic primary pain’, which may be conceived of  as a disease in its own right, for example in condi tions such as fibromyalgia or non-specific low-back pain. In six other subgroups, pain is secondary to an underlying disease: chronic cancer-related pain, chronic neuropa thic pain, chronic secondary visceral pain, chronic post-traumatic and postsurgi cal pain, chronic secondary headache and orofacial pain and chronic secondary musculoskeletal pain. These conditions are summarised as ‘chronic secondary pain’, in which pain may at least initially be conceived as a symptom. In sur gical practice, patients with chronic pain may present for treatment of  the cause (e.g. pancreatitis, malignancy) or concomitant benign pathology . Almost 50 years ago, using gate theor y , Melzeck and Wall proposed pain to be not only subjec tive but also a multidimensional experience that incorporates sensory/discriminative, motivational/a ff ect and cognitive aspects. Recent guidance from the International Association for the Study of  Pain highlights tha t the multidimensional aspect is one of  the key components, hence the treatment of  chronic pain involves a multidisciplinary multimodal approach. Mechanistically , chronic pain may be classified into: /uni25CF Nociceptive pain , which may result from musculoskel etal disorders or cancer activating cutaneous nociceptors (pain receptors). Prolonged ischaemic or inflammatory processes result in sensitisation of  peripheral nociceptor and altered activity in the central nervous system, leading to exaggerated responses in the dorsal horn of  the spinal cord. The widened area of  hyperalgesia and increased sen sitivity (allodynia) have been attributed to increased trans mission in the central nervous system. the peripheral or central nerves (excluding the ‘physiolog - ical’ pain due to noxious stimulation of the nerve termi - nals). It is classically of  a ‘burning’, ‘shooting’ or ‘stabbing’ type and may be associated with allodynia, numbness and diminished thermal sensation. It is poorly responsive to - opioids. Examples include trigeminal neuralgia, posther - petic neuropathy and diabetic neuropathy . -

Common local anaesthesia techniques
Common local anaesthesia techniques
Topical anaesthesia /uni25CF EMLA (eutectic mixture of  local anaesthetics) This is a mixture of  lidocaine and prilocaine for applica tion to the skin for venepuncture in children. Johann Friedrich Horner , 1831–1886, Professor of  Ophthalmology , Zurich, Switzerland, described this syndrome in 1869. Major A. J. Mo ff ett of  the Royal Army Medical Corps first described its use in 1941. He modified it in 1946 to include 2 mL of  8% cocaine, 2 mL of  1% sodium bicarbonate, and 1 mL of  1:1000 adrenaline . - added mixture of  adrenaline and sodium bicarbonate) and used in nasal surgery for anaesthesia and vasoconstriction. /uni25CF - Lidocaine 2/4/10% . Spray to anaesthetise the airway during awake fibreoptic intubation. Nerve blocks - An interscalene approach to brachial plexus for shoulder - surgery produces excellent postoperative analgesia. Compli - cations include phrenic nerve block, Horner’s syndrome and accidental intravascular and spinal injection.  Supraclavicular, infraclavicular or axillary approaches to the brachial plexus can be used as the sole anaesthetic technique for upper limb surger y ( Figure 23.7 ). Femoral and sciatic nerve blocks are often used for anaesthesia and analgesia for lower limb surgery . Local anaesthetic blocks have been described that block the nerves closer to the joint so that motor blockade of  the whole lower limb can be minimised. An example of this type of  block is the iPACK (infiltration between the popliteal artery and capsule of  the knee) block, which targets the genicular nerves supplying the knee joint by using ultrasound-guided injection posterior to the knee joint. Transversus abdominis plane/quadratus lumborum and erector spinae plane block are examples of  fascial plane blocks, which have grown rapidly in popularity . Local anaes - thetic is injected in the fascial planes containing the nerves from abdominal or chest wall structures. Transversus abdom - inis plane (TAP) block has been claimed to provide e ff ective - . -
(a)
(b)
Figure 23.7 (a, b)
Ultrasonic picture of brachial plexus block.
segmental nerves enter the plane between the internal oblique muscle and the transverse abdominis muscle just medial to the anterior axillary line. Injection of local anaesthetic into the fascial plane between the internal oblique and transver sus abdominis muscles allows a block of  all these nerves, and excellent anaesthesia of  the anterior abdominal wall. Quadra tus lumborum block also aims to target abdominal nerves as they pass in front of  the quadratus lumborum muscle. Erector spinae block aims to block the spinal nerv es at various sites, depending on the site of injection. Local anaesthetic is depos ited underneath the erector spinae group of  muscles as they lie over the transverse process of  the vertebra. Intravenous regional anaesthesia (Bier’s block) Bier’s block produces excellent anaesthesia for short surgery , particularly for the upper limb (e.g. carpal tunnel release). In this technique local anaesthetic is injected intravenously to produce anaesthesia of  the upper limb. A double tourniquet is used on the side of  surgery . An intravenous cannula is sited into a vein on the back of  the hand on the side that is being operated on. The upper limb is then exsanguinated using an Esmarch bandage. The proximal cu ff of  the double tourniquet is inflated, followed by intravenous injection of prilocaine into the cannula. After 20 minutes the distal cu ff of  the tourniquet is inflated and then the proximal cu ff is deflated. Even if  surgery is finished, the tourniquet should be left inflated until the local anaesthetic has bound to tissues (20 minutes) so that release of local anaesthetic into the systemic circulation does not occur. Lidocaine can be used with caution (consider the safe dose of lidocaine and the time of  tourniquet inflation) but bupivacaine should never be used for Bier’s block. Spinal anaesthesia Spinal anaesthesia alone or in combination with general anaesthesia or sedation is used extensively for lower limb, obstetric and pelvic surgery . Injection of  a ‘single-shot’ local anaesthetic agent intrathecally produces intense and rapid block for surgery . The addition of opioids provides prolonged postoperative analgesia but carries the risk of  late respiratory depression. Autonomic sympathetic blockade produces hypoten sion, particularly if  the level of  block is above the T10 spinal dermatome. Caution is needed in patients with hypovolaemia and cardiovascular disease. The incidence of  dural punctur e headache can be mini mised by limiting the number of  punctures and using fine-bore pencil-tip needles that are designed to split rather than cut the dura. Epidural anaesthesia Epidural anaesthesia is slower in onset than spinal but has the advantage of  prolonged analgesia by multiple dosing or continuous infusion through a catheter placed in the epidural space. Being slower in onset, the resulting hypotension from sympathetic blockade can be better controlled and can reduce blood loss. August Karl Gustav Bier , 1861–1949, Professor of  Surgery , Bonn (1903–1907) and Berlin (1907–1932), Germany . weak local anaesthetic combined with opioids (such as fen - tanyl) is routinely used for postoperative analgesia. Placement of  an e pidural catheter in the high thoracic region provides - excellent analgesia for a wide variety of  upper abdominal and thoracic surgical operations, enabling early mobilisation and - reducing respiratory complications. Epidural anaesthesia is technically more di ffi cult than spi - nal anaesthesia; it has a higher failure rate and carries the risk of  nerve damage, spinal injuries, accidental spinal injection - of  a large volume of  local anaesthetic, infection and epidural haematoma. Summary box 23.9 Local anaesthetics /uni25CF /uni25CF /uni25CF /uni25CF
EMLA cream for children needing injections
Regional and nerve blocks for limb surgery
Spinal anaesthesia offers a quick onset and a short duration of
anaesthesia
Epidurals are more dif
/f_i
cult but can then be topped up
postoperatively and used as a continuous infusion
Common local anaesthesia techniques
Topical anaesthesia /uni25CF EMLA (eutectic mixture of  local anaesthetics) This is a mixture of  lidocaine and prilocaine for applica tion to the skin for venepuncture in children. Johann Friedrich Horner , 1831–1886, Professor of  Ophthalmology , Zurich, Switzerland, described this syndrome in 1869. Major A. J. Mo ff ett of  the Royal Army Medical Corps first described its use in 1941. He modified it in 1946 to include 2 mL of  8% cocaine, 2 mL of  1% sodium bicarbonate, and 1 mL of  1:1000 adrenaline . - added mixture of  adrenaline and sodium bicarbonate) and used in nasal surgery for anaesthesia and vasoconstriction. /uni25CF - Lidocaine 2/4/10% . Spray to anaesthetise the airway during awake fibreoptic intubation. Nerve blocks - An interscalene approach to brachial plexus for shoulder - surgery produces excellent postoperative analgesia. Compli - cations include phrenic nerve block, Horner’s syndrome and accidental intravascular and spinal injection.  Supraclavicular, infraclavicular or axillary approaches to the brachial plexus can be used as the sole anaesthetic technique for upper limb surger y ( Figure 23.7 ). Femoral and sciatic nerve blocks are often used for anaesthesia and analgesia for lower limb surgery . Local anaesthetic blocks have been described that block the nerves closer to the joint so that motor blockade of  the whole lower limb can be minimised. An example of this type of  block is the iPACK (infiltration between the popliteal artery and capsule of  the knee) block, which targets the genicular nerves supplying the knee joint by using ultrasound-guided injection posterior to the knee joint. Transversus abdominis plane/quadratus lumborum and erector spinae plane block are examples of  fascial plane blocks, which have grown rapidly in popularity . Local anaes - thetic is injected in the fascial planes containing the nerves from abdominal or chest wall structures. Transversus abdom - inis plane (TAP) block has been claimed to provide e ff ective - . -
(a)
(b)
Figure 23.7 (a, b)
Ultrasonic picture of brachial plexus block.
segmental nerves enter the plane between the internal oblique muscle and the transverse abdominis muscle just medial to the anterior axillary line. Injection of local anaesthetic into the fascial plane between the internal oblique and transver sus abdominis muscles allows a block of  all these nerves, and excellent anaesthesia of  the anterior abdominal wall. Quadra tus lumborum block also aims to target abdominal nerves as they pass in front of  the quadratus lumborum muscle. Erector spinae block aims to block the spinal nerv es at various sites, depending on the site of injection. Local anaesthetic is depos ited underneath the erector spinae group of  muscles as they lie over the transverse process of  the vertebra. Intravenous regional anaesthesia (Bier’s block) Bier’s block produces excellent anaesthesia for short surgery , particularly for the upper limb (e.g. carpal tunnel release). In this technique local anaesthetic is injected intravenously to produce anaesthesia of  the upper limb. A double tourniquet is used on the side of  surgery . An intravenous cannula is sited into a vein on the back of  the hand on the side that is being operated on. The upper limb is then exsanguinated using an Esmarch bandage. The proximal cu ff of  the double tourniquet is inflated, followed by intravenous injection of prilocaine into the cannula. After 20 minutes the distal cu ff of  the tourniquet is inflated and then the proximal cu ff is deflated. Even if  surgery is finished, the tourniquet should be left inflated until the local anaesthetic has bound to tissues (20 minutes) so that release of local anaesthetic into the systemic circulation does not occur. Lidocaine can be used with caution (consider the safe dose of lidocaine and the time of  tourniquet inflation) but bupivacaine should never be used for Bier’s block. Spinal anaesthesia Spinal anaesthesia alone or in combination with general anaesthesia or sedation is used extensively for lower limb, obstetric and pelvic surgery . Injection of  a ‘single-shot’ local anaesthetic agent intrathecally produces intense and rapid block for surgery . The addition of opioids provides prolonged postoperative analgesia but carries the risk of  late respiratory depression. Autonomic sympathetic blockade produces hypoten sion, particularly if  the level of  block is above the T10 spinal dermatome. Caution is needed in patients with hypovolaemia and cardiovascular disease. The incidence of  dural punctur e headache can be mini mised by limiting the number of  punctures and using fine-bore pencil-tip needles that are designed to split rather than cut the dura. Epidural anaesthesia Epidural anaesthesia is slower in onset than spinal but has the advantage of  prolonged analgesia by multiple dosing or continuous infusion through a catheter placed in the epidural space. Being slower in onset, the resulting hypotension from sympathetic blockade can be better controlled and can reduce blood loss. August Karl Gustav Bier , 1861–1949, Professor of  Surgery , Bonn (1903–1907) and Berlin (1907–1932), Germany . weak local anaesthetic combined with opioids (such as fen - tanyl) is routinely used for postoperative analgesia. Placement of  an e pidural catheter in the high thoracic region provides - excellent analgesia for a wide variety of  upper abdominal and thoracic surgical operations, enabling early mobilisation and - reducing respiratory complications. Epidural anaesthesia is technically more di ffi cult than spi - nal anaesthesia; it has a higher failure rate and carries the risk of  nerve damage, spinal injuries, accidental spinal injection - of  a large volume of  local anaesthetic, infection and epidural haematoma. Summary box 23.9 Local anaesthetics /uni25CF /uni25CF /uni25CF /uni25CF
EMLA cream for children needing injections
Regional and nerve blocks for limb surgery
Spinal anaesthesia offers a quick onset and a short duration of
anaesthesia
Epidurals are more dif
/f_i
cult but can then be topped up
postoperatively and used as a continuous infusion
Common local anaesthesia techniques
Topical anaesthesia /uni25CF EMLA (eutectic mixture of  local anaesthetics) This is a mixture of  lidocaine and prilocaine for applica tion to the skin for venepuncture in children. Johann Friedrich Horner , 1831–1886, Professor of  Ophthalmology , Zurich, Switzerland, described this syndrome in 1869. Major A. J. Mo ff ett of  the Royal Army Medical Corps first described its use in 1941. He modified it in 1946 to include 2 mL of  8% cocaine, 2 mL of  1% sodium bicarbonate, and 1 mL of  1:1000 adrenaline . - added mixture of  adrenaline and sodium bicarbonate) and used in nasal surgery for anaesthesia and vasoconstriction. /uni25CF - Lidocaine 2/4/10% . Spray to anaesthetise the airway during awake fibreoptic intubation. Nerve blocks - An interscalene approach to brachial plexus for shoulder - surgery produces excellent postoperative analgesia. Compli - cations include phrenic nerve block, Horner’s syndrome and accidental intravascular and spinal injection.  Supraclavicular, infraclavicular or axillary approaches to the brachial plexus can be used as the sole anaesthetic technique for upper limb surger y ( Figure 23.7 ). Femoral and sciatic nerve blocks are often used for anaesthesia and analgesia for lower limb surgery . Local anaesthetic blocks have been described that block the nerves closer to the joint so that motor blockade of  the whole lower limb can be minimised. An example of this type of  block is the iPACK (infiltration between the popliteal artery and capsule of  the knee) block, which targets the genicular nerves supplying the knee joint by using ultrasound-guided injection posterior to the knee joint. Transversus abdominis plane/quadratus lumborum and erector spinae plane block are examples of  fascial plane blocks, which have grown rapidly in popularity . Local anaes - thetic is injected in the fascial planes containing the nerves from abdominal or chest wall structures. Transversus abdom - inis plane (TAP) block has been claimed to provide e ff ective - . -
(a)
(b)
Figure 23.7 (a, b)
Ultrasonic picture of brachial plexus block.
segmental nerves enter the plane between the internal oblique muscle and the transverse abdominis muscle just medial to the anterior axillary line. Injection of local anaesthetic into the fascial plane between the internal oblique and transver sus abdominis muscles allows a block of  all these nerves, and excellent anaesthesia of  the anterior abdominal wall. Quadra tus lumborum block also aims to target abdominal nerves as they pass in front of  the quadratus lumborum muscle. Erector spinae block aims to block the spinal nerv es at various sites, depending on the site of injection. Local anaesthetic is depos ited underneath the erector spinae group of  muscles as they lie over the transverse process of  the vertebra. Intravenous regional anaesthesia (Bier’s block) Bier’s block produces excellent anaesthesia for short surgery , particularly for the upper limb (e.g. carpal tunnel release). In this technique local anaesthetic is injected intravenously to produce anaesthesia of  the upper limb. A double tourniquet is used on the side of  surgery . An intravenous cannula is sited into a vein on the back of  the hand on the side that is being operated on. The upper limb is then exsanguinated using an Esmarch bandage. The proximal cu ff of  the double tourniquet is inflated, followed by intravenous injection of prilocaine into the cannula. After 20 minutes the distal cu ff of  the tourniquet is inflated and then the proximal cu ff is deflated. Even if  surgery is finished, the tourniquet should be left inflated until the local anaesthetic has bound to tissues (20 minutes) so that release of local anaesthetic into the systemic circulation does not occur. Lidocaine can be used with caution (consider the safe dose of lidocaine and the time of  tourniquet inflation) but bupivacaine should never be used for Bier’s block. Spinal anaesthesia Spinal anaesthesia alone or in combination with general anaesthesia or sedation is used extensively for lower limb, obstetric and pelvic surgery . Injection of  a ‘single-shot’ local anaesthetic agent intrathecally produces intense and rapid block for surgery . The addition of opioids provides prolonged postoperative analgesia but carries the risk of  late respiratory depression. Autonomic sympathetic blockade produces hypoten sion, particularly if  the level of  block is above the T10 spinal dermatome. Caution is needed in patients with hypovolaemia and cardiovascular disease. The incidence of  dural punctur e headache can be mini mised by limiting the number of  punctures and using fine-bore pencil-tip needles that are designed to split rather than cut the dura. Epidural anaesthesia Epidural anaesthesia is slower in onset than spinal but has the advantage of  prolonged analgesia by multiple dosing or continuous infusion through a catheter placed in the epidural space. Being slower in onset, the resulting hypotension from sympathetic blockade can be better controlled and can reduce blood loss. August Karl Gustav Bier , 1861–1949, Professor of  Surgery , Bonn (1903–1907) and Berlin (1907–1932), Germany . weak local anaesthetic combined with opioids (such as fen - tanyl) is routinely used for postoperative analgesia. Placement of  an e pidural catheter in the high thoracic region provides - excellent analgesia for a wide variety of  upper abdominal and thoracic surgical operations, enabling early mobilisation and - reducing respiratory complications. Epidural anaesthesia is technically more di ffi cult than spi - nal anaesthesia; it has a higher failure rate and carries the risk of  nerve damage, spinal injuries, accidental spinal injection - of  a large volume of  local anaesthetic, infection and epidural haematoma. Summary box 23.9 Local anaesthetics /uni25CF /uni25CF /uni25CF /uni25CF
EMLA cream for children needing injections
Regional and nerve blocks for limb surgery
Spinal anaesthesia offers a quick onset and a short duration of
anaesthesia
Epidurals are more dif
/f_i
cult but can then be topped up
postoperatively and used as a continuous infusion

GENERAL ANAESTHESIA
GENERAL ANAESTHESIA
General anaesthesia is commonly described as the triad of unconsciousness, analgesia and muscle relaxation. Summary box 23.2 The general anaesthetic triad /uni25CF /uni25CF /uni25CF Induction of  general anaesthesia is most frequently done by intravenous agents. Propofol has replaced thiopentone as the most widely used induction agent and can be used for main tenance of  anaesthesia. Other infrequently used intravenous agents include etomidate and ketamine. Newer agents based on a benzodiazepine receptor agonist, etomidate derivatives and fospropofol are still in the experimental stage . Inhalational induction using agents such as non-pungent sevoflurane is useful in children, needle-phobic adults and those in whom a di ffi cult airway is anticipated. These patients will have a higher risk of de veloping airway obstruction. Figure 23.1 shows a commonly used anaesthetic machine. Summary box 23.3 Key features of commonly used intravenous anaesthetic agents /uni25CF /uni25CF /uni25CF /uni25CF Rapid sequence induction (RSI) using a predeter mined dose of  intravenous anaesthetic agent together with a rapidly acting muscle relaxant is used in those with a high risk of  regurgitation in order to secure the airway quickly . Com monly needed in emergency surgery , it is also a technique of - choice in any non-emergency surgery in a patient with delayed emptying of  the stomach. T otal intravenous anaesthesia (TIV A) is becoming popular following the introduction of  propofol and the ultra - short-acting opioid remifentanil. The lack of  cumulative e ff ect, better haemodynamic stability , excellent recovery profile and concerns over environmental e ff ects of  inhalational agents hav e made TIV A an attractive choice. TIV A is routinely used in neurosurgery , airway laser surgery , during cardiopulmonary bypass and for day case anaesthesia. Summary box 23.4 Special terms in anaesthesia /uni25CF /uni25CF Maintenance of  anaesthesia can be done using a contin - uous infusion of intravenous agent (propofol) or an inhaled - vapour such as isoflurane, sevoflurane or desflurane. The use of  nitrous oxide is declining, despite its analgesic and weak anaesthetic properties, because of concerns over - postoperative nausea and vomiting. It also incr eases the size
Amnesia: loss of awareness
Analgesia: pain relief
Muscle relaxation
Propofol (di-isopropyl phenol)
: smooth induction, better
haemodynamic stability, blunting of autonomic re
/f_l
exes and
ability to use as a continuous infusion
Thiopentone (barbiturate)
: rapid induction, myocardial
depression. A reduced metabolic rate and lowering of
intracranial pressure is useful in neurosurgical patients but the
drop in blood pressure can have detrimental effects
Etomidate (steroid derivative)
: good haemodynamic stability,
brief duration of action, but concern over adrenocortical
depression
Ketamine (phencyclidine derivative)
: preservation of blood
pressure and respiratory re
/f_l
exes together with excellent
analgesia makes it an ideal choice for
/f_i
eld anaesthesia.
Emergence delirium is associated with administration of
ketamine
Figure 23.1
Anaesthetic machine.
RSI is a technique that allows the airway to be rapidly
secured. It is used when there is a high risk of regurgitation
that may lead to pulmonary aspiration
TIVA is becoming increasingly popular
and abdominal surgery . Finally it is possibly mutagenic and is a powerful greenhouse gas. GENERAL ANAESTHESIA
General anaesthesia is commonly described as the triad of unconsciousness, analgesia and muscle relaxation. Summary box 23.2 The general anaesthetic triad /uni25CF /uni25CF /uni25CF Induction of  general anaesthesia is most frequently done by intravenous agents. Propofol has replaced thiopentone as the most widely used induction agent and can be used for main tenance of  anaesthesia. Other infrequently used intravenous agents include etomidate and ketamine. Newer agents based on a benzodiazepine receptor agonist, etomidate derivatives and fospropofol are still in the experimental stage . Inhalational induction using agents such as non-pungent sevoflurane is useful in children, needle-phobic adults and those in whom a di ffi cult airway is anticipated. These patients will have a higher risk of de veloping airway obstruction. Figure 23.1 shows a commonly used anaesthetic machine. Summary box 23.3 Key features of commonly used intravenous anaesthetic agents /uni25CF /uni25CF /uni25CF /uni25CF Rapid sequence induction (RSI) using a predeter mined dose of  intravenous anaesthetic agent together with a rapidly acting muscle relaxant is used in those with a high risk of  regurgitation in order to secure the airway quickly . Com monly needed in emergency surgery , it is also a technique of - choice in any non-emergency surgery in a patient with delayed emptying of  the stomach. T otal intravenous anaesthesia (TIV A) is becoming popular following the introduction of  propofol and the ultra - short-acting opioid remifentanil. The lack of  cumulative e ff ect, better haemodynamic stability , excellent recovery profile and concerns over environmental e ff ects of  inhalational agents hav e made TIV A an attractive choice. TIV A is routinely used in neurosurgery , airway laser surgery , during cardiopulmonary bypass and for day case anaesthesia. Summary box 23.4 Special terms in anaesthesia /uni25CF /uni25CF Maintenance of  anaesthesia can be done using a contin - uous infusion of intravenous agent (propofol) or an inhaled - vapour such as isoflurane, sevoflurane or desflurane. The use of  nitrous oxide is declining, despite its analgesic and weak anaesthetic properties, because of concerns over - postoperative nausea and vomiting. It also incr eases the size
Amnesia: loss of awareness
Analgesia: pain relief
Muscle relaxation
Propofol (di-isopropyl phenol)
: smooth induction, better
haemodynamic stability, blunting of autonomic re
/f_l
exes and
ability to use as a continuous infusion
Thiopentone (barbiturate)
: rapid induction, myocardial
depression. A reduced metabolic rate and lowering of
intracranial pressure is useful in neurosurgical patients but the
drop in blood pressure can have detrimental effects
Etomidate (steroid derivative)
: good haemodynamic stability,
brief duration of action, but concern over adrenocortical
depression
Ketamine (phencyclidine derivative)
: preservation of blood
pressure and respiratory re
/f_l
exes together with excellent
analgesia makes it an ideal choice for
/f_i
eld anaesthesia.
Emergence delirium is associated with administration of
ketamine
Figure 23.1
Anaesthetic machine.
RSI is a technique that allows the airway to be rapidly
secured. It is used when there is a high risk of regurgitation
that may lead to pulmonary aspiration
TIVA is becoming increasingly popular
and abdominal surgery . Finally it is possibly mutagenic and is a powerful greenhouse gas. GENERAL ANAESTHESIA
General anaesthesia is commonly described as the triad of unconsciousness, analgesia and muscle relaxation. Summary box 23.2 The general anaesthetic triad /uni25CF /uni25CF /uni25CF Induction of  general anaesthesia is most frequently done by intravenous agents. Propofol has replaced thiopentone as the most widely used induction agent and can be used for main tenance of  anaesthesia. Other infrequently used intravenous agents include etomidate and ketamine. Newer agents based on a benzodiazepine receptor agonist, etomidate derivatives and fospropofol are still in the experimental stage . Inhalational induction using agents such as non-pungent sevoflurane is useful in children, needle-phobic adults and those in whom a di ffi cult airway is anticipated. These patients will have a higher risk of de veloping airway obstruction. Figure 23.1 shows a commonly used anaesthetic machine. Summary box 23.3 Key features of commonly used intravenous anaesthetic agents /uni25CF /uni25CF /uni25CF /uni25CF Rapid sequence induction (RSI) using a predeter mined dose of  intravenous anaesthetic agent together with a rapidly acting muscle relaxant is used in those with a high risk of  regurgitation in order to secure the airway quickly . Com monly needed in emergency surgery , it is also a technique of - choice in any non-emergency surgery in a patient with delayed emptying of  the stomach. T otal intravenous anaesthesia (TIV A) is becoming popular following the introduction of  propofol and the ultra - short-acting opioid remifentanil. The lack of  cumulative e ff ect, better haemodynamic stability , excellent recovery profile and concerns over environmental e ff ects of  inhalational agents hav e made TIV A an attractive choice. TIV A is routinely used in neurosurgery , airway laser surgery , during cardiopulmonary bypass and for day case anaesthesia. Summary box 23.4 Special terms in anaesthesia /uni25CF /uni25CF Maintenance of  anaesthesia can be done using a contin - uous infusion of intravenous agent (propofol) or an inhaled - vapour such as isoflurane, sevoflurane or desflurane. The use of  nitrous oxide is declining, despite its analgesic and weak anaesthetic properties, because of concerns over - postoperative nausea and vomiting. It also incr eases the size
Amnesia: loss of awareness
Analgesia: pain relief
Muscle relaxation
Propofol (di-isopropyl phenol)
: smooth induction, better
haemodynamic stability, blunting of autonomic re
/f_l
exes and
ability to use as a continuous infusion
Thiopentone (barbiturate)
: rapid induction, myocardial
depression. A reduced metabolic rate and lowering of
intracranial pressure is useful in neurosurgical patients but the
drop in blood pressure can have detrimental effects
Etomidate (steroid derivative)
: good haemodynamic stability,
brief duration of action, but concern over adrenocortical
depression
Ketamine (phencyclidine derivative)
: preservation of blood
pressure and respiratory re
/f_l
exes together with excellent
analgesia makes it an ideal choice for
/f_i
eld anaesthesia.
Emergence delirium is associated with administration of
ketamine
Figure 23.1
Anaesthetic machine.
RSI is a technique that allows the airway to be rapidly
secured. It is used when there is a high risk of regurgitation
that may lead to pulmonary aspiration
TIVA is becoming increasingly popular
and abdominal surgery . Finally it is possibly mutagenic and is a powerful greenhouse gas.

HISTORY
HISTORY
Anaesthesia, as we know it today , was first successfully demon strated by William Morton, a local dentist, at the Massachu setts General Hospital, Boston, MA, USA on 16 October 1846 when he administered ether to Gilbert Abbot for an operation on a vascular tumour on his neck. Earlier Horace Wells had used nitrous oxide in 1844 for painless extraction of  teeth successfully . Simpson, at Edinburgh Univ ersity , overcame some of  the technical di ffi culties of  ether administration by introducing chloroform. The benefits of  anaesthesia were then universally recognised and antagonism by r eligious leaders was countered when Queen Victoria accepted chloroform from John Snow during the birth of  Prince Leopold in 1853. HISTORY
Anaesthesia, as we know it today , was first successfully demon strated by William Morton, a local dentist, at the Massachu setts General Hospital, Boston, MA, USA on 16 October 1846 when he administered ether to Gilbert Abbot for an operation on a vascular tumour on his neck. Earlier Horace Wells had used nitrous oxide in 1844 for painless extraction of  teeth successfully . Simpson, at Edinburgh Univ ersity , overcame some of  the technical di ffi culties of  ether administration by introducing chloroform. The benefits of  anaesthesia were then universally recognised and antagonism by r eligious leaders was countered when Queen Victoria accepted chloroform from John Snow during the birth of  Prince Leopold in 1853. HISTORY
Anaesthesia, as we know it today , was first successfully demon strated by William Morton, a local dentist, at the Massachu setts General Hospital, Boston, MA, USA on 16 October 1846 when he administered ether to Gilbert Abbot for an operation on a vascular tumour on his neck. Earlier Horace Wells had used nitrous oxide in 1844 for painless extraction of  teeth successfully . Simpson, at Edinburgh Univ ersity , overcame some of  the technical di ffi culties of  ether administration by introducing chloroform. The benefits of  anaesthesia were then universally recognised and antagonism by r eligious leaders was countered when Queen Victoria accepted chloroform from John Snow during the birth of  Prince Leopold in 1853.

Introduction
Introduction
No content extracted automatically.

KEY PRINCIPLES OF ANAESTHESIA
KEY PRINCIPLES OF ANAESTHESIA
Optimum patient care is dependent on a collaborative approach by the anaesthetic and surgical teams. The importance of multidisciplinary collaboration has been clearly demonstrated by national audits such as the National Confidential Enquiry into Patient Outcome and Death (NCEPOD) and the Confi dential Enquiry into Maternal Deaths in the UK. These audits have led to changes in clinical and non-clinical practice to improve morbidity and mortality . The use of  a safety checklist in operating theatres in the form of  the Wor ld Health Organization’s (WHO) ‘WHO Anaesthesia ; the name was suggested by Oliver Wendell-Homes, first appeared in Bailey’s William Thomas Gren Morton , 1819–1868, dentist who practised in Boston, MA, USA. Horace Wells , 1815–1848, Harvard, CT , USA, dentist who pioneered the use of  nitrous oxide anaesthesia to prevent pain during dental procedures. Sir James Y oung Simpson , 1811–1870, Professor of  Midwifery , Edinburgh, UK. John Snow , 1813–1858, general practitioner, London, UK, was one of  the pioneers of  anaesthesia. Humphrey Davy , 1800, suggested that nitrous oxide inhalation might be used to relieve the pain of  surgical operations and named it ‘laughing gas’. Henry Edmund Gaskin Boyle , in 1917, got his gas-oxygen machine, which became the first ‘Boyle apparatus’. The first examination for a Diploma in Anaesthesia was held in London in 1935. The First Chair in Anaesthesia : Ralph Waters, Wisconsin, USA, in 1933 and RR Macintosh in Oxford, UK, in 1937. During the First World War Sir Ivan Magill and Stanley Rowbotham bation. Sir Magill is also remembered for his laryngoscope, Magill attachment and laryngeal forceps. Surgical Safety Checklist’ has shown a reduction in the inci - dence of  perioperative untoward events. - The role of the modern anaesthetist has evolved from just - being responsible for the patient in the operating suite into a ‘perioperative physician’ who optimises the patient for surger y , assesses and minimises risk, cares for the patient during the operation and then manages both pain and homeostasis in the postoperative period. Summary box 23.1 Ground rules for anaesthesia /uni25CF /uni25CF /uni25CF /uni25CF -
Local and regional anaesthesia techniques
•
The management of chronic pain and pain from malignant
•
disease
Safe surgery is achieved by close teamwork between the
surgeon and the anaesthetist
Safety checklists ensure that things are not forgotten
Risk assessments allow the best strategy to be chosen
Anaesthetists are extending their care into the pre- and
postoperative phases
KEY PRINCIPLES OF ANAESTHESIA
Optimum patient care is dependent on a collaborative approach by the anaesthetic and surgical teams. The importance of multidisciplinary collaboration has been clearly demonstrated by national audits such as the National Confidential Enquiry into Patient Outcome and Death (NCEPOD) and the Confi dential Enquiry into Maternal Deaths in the UK. These audits have led to changes in clinical and non-clinical practice to improve morbidity and mortality . The use of  a safety checklist in operating theatres in the form of  the Wor ld Health Organization’s (WHO) ‘WHO Anaesthesia ; the name was suggested by Oliver Wendell-Homes, first appeared in Bailey’s William Thomas Gren Morton , 1819–1868, dentist who practised in Boston, MA, USA. Horace Wells , 1815–1848, Harvard, CT , USA, dentist who pioneered the use of  nitrous oxide anaesthesia to prevent pain during dental procedures. Sir James Y oung Simpson , 1811–1870, Professor of  Midwifery , Edinburgh, UK. John Snow , 1813–1858, general practitioner, London, UK, was one of  the pioneers of  anaesthesia. Humphrey Davy , 1800, suggested that nitrous oxide inhalation might be used to relieve the pain of  surgical operations and named it ‘laughing gas’. Henry Edmund Gaskin Boyle , in 1917, got his gas-oxygen machine, which became the first ‘Boyle apparatus’. The first examination for a Diploma in Anaesthesia was held in London in 1935. The First Chair in Anaesthesia : Ralph Waters, Wisconsin, USA, in 1933 and RR Macintosh in Oxford, UK, in 1937. During the First World War Sir Ivan Magill and Stanley Rowbotham bation. Sir Magill is also remembered for his laryngoscope, Magill attachment and laryngeal forceps. Surgical Safety Checklist’ has shown a reduction in the inci - dence of  perioperative untoward events. - The role of the modern anaesthetist has evolved from just - being responsible for the patient in the operating suite into a ‘perioperative physician’ who optimises the patient for surger y , assesses and minimises risk, cares for the patient during the operation and then manages both pain and homeostasis in the postoperative period. Summary box 23.1 Ground rules for anaesthesia /uni25CF /uni25CF /uni25CF /uni25CF -
Local and regional anaesthesia techniques
•
The management of chronic pain and pain from malignant
•
disease
Safe surgery is achieved by close teamwork between the
surgeon and the anaesthetist
Safety checklists ensure that things are not forgotten
Risk assessments allow the best strategy to be chosen
Anaesthetists are extending their care into the pre- and
postoperative phases
KEY PRINCIPLES OF ANAESTHESIA
Optimum patient care is dependent on a collaborative approach by the anaesthetic and surgical teams. The importance of multidisciplinary collaboration has been clearly demonstrated by national audits such as the National Confidential Enquiry into Patient Outcome and Death (NCEPOD) and the Confi dential Enquiry into Maternal Deaths in the UK. These audits have led to changes in clinical and non-clinical practice to improve morbidity and mortality . The use of  a safety checklist in operating theatres in the form of  the Wor ld Health Organization’s (WHO) ‘WHO Anaesthesia ; the name was suggested by Oliver Wendell-Homes, first appeared in Bailey’s William Thomas Gren Morton , 1819–1868, dentist who practised in Boston, MA, USA. Horace Wells , 1815–1848, Harvard, CT , USA, dentist who pioneered the use of  nitrous oxide anaesthesia to prevent pain during dental procedures. Sir James Y oung Simpson , 1811–1870, Professor of  Midwifery , Edinburgh, UK. John Snow , 1813–1858, general practitioner, London, UK, was one of  the pioneers of  anaesthesia. Humphrey Davy , 1800, suggested that nitrous oxide inhalation might be used to relieve the pain of  surgical operations and named it ‘laughing gas’. Henry Edmund Gaskin Boyle , in 1917, got his gas-oxygen machine, which became the first ‘Boyle apparatus’. The first examination for a Diploma in Anaesthesia was held in London in 1935. The First Chair in Anaesthesia : Ralph Waters, Wisconsin, USA, in 1933 and RR Macintosh in Oxford, UK, in 1937. During the First World War Sir Ivan Magill and Stanley Rowbotham bation. Sir Magill is also remembered for his laryngoscope, Magill attachment and laryngeal forceps. Surgical Safety Checklist’ has shown a reduction in the inci - dence of  perioperative untoward events. - The role of the modern anaesthetist has evolved from just - being responsible for the patient in the operating suite into a ‘perioperative physician’ who optimises the patient for surger y , assesses and minimises risk, cares for the patient during the operation and then manages both pain and homeostasis in the postoperative period. Summary box 23.1 Ground rules for anaesthesia /uni25CF /uni25CF /uni25CF /uni25CF -
Local and regional anaesthesia techniques
•
The management of chronic pain and pain from malignant
•
disease
Safe surgery is achieved by close teamwork between the
surgeon and the anaesthetist
Safety checklists ensure that things are not forgotten
Risk assessments allow the best strategy to be chosen
Anaesthetists are extending their care into the pre- and
postoperative phases

LOCAL ANAESTHESIA
LOCAL ANAESTHESIA
Local anaesthetic drugs ( Table 23.2 ) may be used to provide anaesthesia and analgesia, as a sole agent or as adjuncts to general anaesthesia. Available techniques include topical anaesthesia, local infiltration, regional nerve blocks and central neuraxial blocks (spinal and epidural anaesthesia). Local anaesthesia techniques can lead to complications that may be local, such as infection or haematoma, or systemic, as a result of  overdose or accidental intravascular injection.
TABLE 23.2
The common local anaesthetic drugs.
Name
Maximum dose
Comments
Early onset, short
Lidocaine
3
/uni00A0
mg/kg (7
/uni00A0
mg/kg
acting, good sensory
with adrenaline
block
[epinephrine])
Bupivacaine
2
/uni00A0
mg/kg
Long lasting, more
cardiotoxic, must never
be used intravenously
Prilocaine
6
/uni00A0
mg/kg (9
/uni00A0
mg/kg
Least systemic
with adrenaline)
toxicity, causes
methaemoglobinaemia
Ropivacaine
3–4
/uni00A0
mg/kg
Less cardiotoxic,
greater sensory–motor
separation
Levobupivacaine
2
/uni00A0
mg/kg
Isomer of bupivacaine
with fewer cardiotoxic
properties
dependent and manifest as cardiovascular (cardiac arrhyth mia, cardiac arrest) or neurological (depressed consciousness, convulsions). Prilocaine overdose causes methaemoglobinae mia, whereas bupivacaine overdose causes treatment-resistant ventricular ar rhythmia and cardiac arrest. The addition of  adrenaline (epinephrine) to local anaes thetic solutions hastens onset, prolongs the duration of  action and permits a higher upper dose limit. The use of adrena line is contraindicated in patients with cardiovascular disease, those taking tricyclic and monoamine oxidase inhibitors and in end-arterial locations. Appr opriately skilled personnel, resuscitation equipment and oxygen should alwa ys be available with local anaesthetic use because of  the potential risks of  life-threatening complications. LOCAL ANAESTHESIA
Local anaesthetic drugs ( Table 23.2 ) may be used to provide anaesthesia and analgesia, as a sole agent or as adjuncts to general anaesthesia. Available techniques include topical anaesthesia, local infiltration, regional nerve blocks and central neuraxial blocks (spinal and epidural anaesthesia). Local anaesthesia techniques can lead to complications that may be local, such as infection or haematoma, or systemic, as a result of  overdose or accidental intravascular injection.
TABLE 23.2
The common local anaesthetic drugs.
Name
Maximum dose
Comments
Early onset, short
Lidocaine
3
/uni00A0
mg/kg (7
/uni00A0
mg/kg
acting, good sensory
with adrenaline
block
[epinephrine])
Bupivacaine
2
/uni00A0
mg/kg
Long lasting, more
cardiotoxic, must never
be used intravenously
Prilocaine
6
/uni00A0
mg/kg (9
/uni00A0
mg/kg
Least systemic
with adrenaline)
toxicity, causes
methaemoglobinaemia
Ropivacaine
3–4
/uni00A0
mg/kg
Less cardiotoxic,
greater sensory–motor
separation
Levobupivacaine
2
/uni00A0
mg/kg
Isomer of bupivacaine
with fewer cardiotoxic
properties
dependent and manifest as cardiovascular (cardiac arrhyth mia, cardiac arrest) or neurological (depressed consciousness, convulsions). Prilocaine overdose causes methaemoglobinae mia, whereas bupivacaine overdose causes treatment-resistant ventricular ar rhythmia and cardiac arrest. The addition of  adrenaline (epinephrine) to local anaes thetic solutions hastens onset, prolongs the duration of  action and permits a higher upper dose limit. The use of adrena line is contraindicated in patients with cardiovascular disease, those taking tricyclic and monoamine oxidase inhibitors and in end-arterial locations. Appr opriately skilled personnel, resuscitation equipment and oxygen should alwa ys be available with local anaesthetic use because of  the potential risks of  life-threatening complications. LOCAL ANAESTHESIA
Local anaesthetic drugs ( Table 23.2 ) may be used to provide anaesthesia and analgesia, as a sole agent or as adjuncts to general anaesthesia. Available techniques include topical anaesthesia, local infiltration, regional nerve blocks and central neuraxial blocks (spinal and epidural anaesthesia). Local anaesthesia techniques can lead to complications that may be local, such as infection or haematoma, or systemic, as a result of  overdose or accidental intravascular injection.
TABLE 23.2
The common local anaesthetic drugs.
Name
Maximum dose
Comments
Early onset, short
Lidocaine
3
/uni00A0
mg/kg (7
/uni00A0
mg/kg
acting, good sensory
with adrenaline
block
[epinephrine])
Bupivacaine
2
/uni00A0
mg/kg
Long lasting, more
cardiotoxic, must never
be used intravenously
Prilocaine
6
/uni00A0
mg/kg (9
/uni00A0
mg/kg
Least systemic
with adrenaline)
toxicity, causes
methaemoglobinaemia
Ropivacaine
3–4
/uni00A0
mg/kg
Less cardiotoxic,
greater sensory–motor
separation
Levobupivacaine
2
/uni00A0
mg/kg
Isomer of bupivacaine
with fewer cardiotoxic
properties
dependent and manifest as cardiovascular (cardiac arrhyth mia, cardiac arrest) or neurological (depressed consciousness, convulsions). Prilocaine overdose causes methaemoglobinae mia, whereas bupivacaine overdose causes treatment-resistant ventricular ar rhythmia and cardiac arrest. The addition of  adrenaline (epinephrine) to local anaes thetic solutions hastens onset, prolongs the duration of  action and permits a higher upper dose limit. The use of adrena line is contraindicated in patients with cardiovascular disease, those taking tricyclic and monoamine oxidase inhibitors and in end-arterial locations. Appr opriately skilled personnel, resuscitation equipment and oxygen should alwa ys be available with local anaesthetic use because of  the potential risks of  life-threatening complications.

Learning objectives
Learning objectives
To gain an understanding of: Techniques of anaesthesia and airway maintenance • Methods of providing pain relief • Learning objectives
To gain an understanding of: Techniques of anaesthesia and airway maintenance • Methods of providing pain relief • Learning objectives
To gain an understanding of: Techniques of anaesthesia and airway maintenance • Methods of providing pain relief •

Management of the airway during anaesthesia
Management of the airway during anaesthesia
Loss of  muscle tone as a result of  general anaesthesia means that the patient can no longer keep their airway open. There fore, patients need their airway to be maintained for them. The use of  muscle relaxants will mean that they will also be unable to breathe for themselves and so will require artificial ventilation. Head tilt, chin lift and jaw thrust manoeuvr es along with adjuncts such as oropharyngeal airways ( Figure 23.2 used to facilitate bag–mask ventilation while induction agents exert their full e ff ect. A laryngeal mask airway or endotracheal tube is then inserted, and the patient is allowed to breathe spontaneously or is ventilated during the procedure. The addition of a cu ff to the endo-tracheal tube facilitates positive pressure ventilation and protects the lungs from aspi ration of  regurgitated gastric contents. Supraglottic airways /uni25CF Laryngeal mask airway (LMA) . Developed by Dr Archie Brain in the UK, the original LMA first-generation supraglottic airway . The mask with an inflatable cu ff is inserted via the mouth and produces a seal around the glottic opening, providing a very reliable means of  maintaining the airway . Its placement is less irritating and less traumatic to a patient’s airway than endotracheal intubation. The technique can be easily taught to non anaesthetists and paramedics and can be used as an emergency airway management tool. Several varieties of first-generation LMAs are available, including the classic LMA and the flexible LMA. Further advancements ha led to the development of  second-generation supraglottic ® devices, such as the ProSeal LMA and the i-gel ( Figure 23.3 ). These devices usually have an in-built ‘bite block’ and oesophageal drain tube. They can be used for ventilation of  the lungs at higher inflation pressures and are more suitable for patients with a higher body mass index. There are also modified versions of  the LMA, including the ILMA (intubating LMA), that allow a blind technique, aiding insertion of  a tracheal tube in di ffi cult conditions. Archie Brain , b. 1942, formally an anaesthetist, whose patent application for the laryngeal mask airway was granted in 1982. devices have a good safety and e ffi cacy profile and should be replacing all first-generation devices. /uni25CF Di ffi cult intubation . Endotracheal intubation is feasible in most patients, but in a certain proportion of patients it may be di ffi cult or impossible. However, if  it is compounded by an inability to ventilate and therefore maintain oxygenation of  the patient by bag–mask, the consequence can be catastrophic hypoxia. Many devices - have been developed to aid intubation if  di ffi culty is ® ® ® anticipated (e.g. McGrath blade, Airtraq , C-MAC video laryngoscope) ( Figures 23.4 and 23.5 ); similarly , protocols have been created by specialised societies to deal ) are - ® is a - ve ®
Figure 23.2
Oropharyngeal airways.
®
Figure 23.3
i-gel
supraglottic airway.
Figure 23.4
Single-use laryngoscope.
with such situations. One specialised method for intubation in di ffi cult situations is the use of the fibreoptic intubating bronchoscope ( Figure 23.6 ), facilitated by topical local anaesthetic in awake patients or using general anaesthesia. The anaesthetist places the endotracheal tube in the trachea by threading the tube over the bronchoscope, and so places the tube in the trachea under direct bronchoscopic vision. An awake intubation requires careful patient selection, as it may not be a suitable technique for all patient groups. Double-lumen tubes and endobronchial tubes are used in procedures such as thoracoscopic, pulmonary and oesophageal surgery to allow collapse of  one lung (while ventilating the other) for ease of  surgery . Their use is also essential to isola healthy lung in empyema and in the case of  a bronchopleural fistula. V entilating bronchoscopes and endobronchial catheters can be used to maintain oxygenation during laryngotracheal surgery or bronchoscopy by using intermittent jets of  oxygen. Arthur Ernest Guedel , 1883–1956, Clinical Professor of  Anesthesiology , University of  Southern California, Los Angeles, CA, USA. Techniques for maintaining an airway /uni25CF /uni25CF /uni25CF /uni25CF Summary box 23.6 Complications of intubation /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF
®
Figure 23.5
Airtraq
intubating device.
Figure 23.6
Fibreoptic intubating bronchoscope.
Chin lift and jaw thrust: suitable for the short term when no aid
is available
Guedel airway: holds the tongue forward but does not prevent
aspiration
Supraglottic device: easy insertion, reliable airway, allows
ventilation
Endotracheal intubation: secure and protected airway
Failed intubation
Accidental bronchial intubation
Trauma to teeth, pharynx or larynx
Aspiration of gastric contents during intubation
Disconnection, blockage or kinking of tube
Delayed tracheal stenosis
Management of the airway during anaesthesia
Loss of  muscle tone as a result of  general anaesthesia means that the patient can no longer keep their airway open. There fore, patients need their airway to be maintained for them. The use of  muscle relaxants will mean that they will also be unable to breathe for themselves and so will require artificial ventilation. Head tilt, chin lift and jaw thrust manoeuvr es along with adjuncts such as oropharyngeal airways ( Figure 23.2 used to facilitate bag–mask ventilation while induction agents exert their full e ff ect. A laryngeal mask airway or endotracheal tube is then inserted, and the patient is allowed to breathe spontaneously or is ventilated during the procedure. The addition of a cu ff to the endo-tracheal tube facilitates positive pressure ventilation and protects the lungs from aspi ration of  regurgitated gastric contents. Supraglottic airways /uni25CF Laryngeal mask airway (LMA) . Developed by Dr Archie Brain in the UK, the original LMA first-generation supraglottic airway . The mask with an inflatable cu ff is inserted via the mouth and produces a seal around the glottic opening, providing a very reliable means of  maintaining the airway . Its placement is less irritating and less traumatic to a patient’s airway than endotracheal intubation. The technique can be easily taught to non anaesthetists and paramedics and can be used as an emergency airway management tool. Several varieties of first-generation LMAs are available, including the classic LMA and the flexible LMA. Further advancements ha led to the development of  second-generation supraglottic ® devices, such as the ProSeal LMA and the i-gel ( Figure 23.3 ). These devices usually have an in-built ‘bite block’ and oesophageal drain tube. They can be used for ventilation of  the lungs at higher inflation pressures and are more suitable for patients with a higher body mass index. There are also modified versions of  the LMA, including the ILMA (intubating LMA), that allow a blind technique, aiding insertion of  a tracheal tube in di ffi cult conditions. Archie Brain , b. 1942, formally an anaesthetist, whose patent application for the laryngeal mask airway was granted in 1982. devices have a good safety and e ffi cacy profile and should be replacing all first-generation devices. /uni25CF Di ffi cult intubation . Endotracheal intubation is feasible in most patients, but in a certain proportion of patients it may be di ffi cult or impossible. However, if  it is compounded by an inability to ventilate and therefore maintain oxygenation of  the patient by bag–mask, the consequence can be catastrophic hypoxia. Many devices - have been developed to aid intubation if  di ffi culty is ® ® ® anticipated (e.g. McGrath blade, Airtraq , C-MAC video laryngoscope) ( Figures 23.4 and 23.5 ); similarly , protocols have been created by specialised societies to deal ) are - ® is a - ve ®
Figure 23.2
Oropharyngeal airways.
®
Figure 23.3
i-gel
supraglottic airway.
Figure 23.4
Single-use laryngoscope.
with such situations. One specialised method for intubation in di ffi cult situations is the use of the fibreoptic intubating bronchoscope ( Figure 23.6 ), facilitated by topical local anaesthetic in awake patients or using general anaesthesia. The anaesthetist places the endotracheal tube in the trachea by threading the tube over the bronchoscope, and so places the tube in the trachea under direct bronchoscopic vision. An awake intubation requires careful patient selection, as it may not be a suitable technique for all patient groups. Double-lumen tubes and endobronchial tubes are used in procedures such as thoracoscopic, pulmonary and oesophageal surgery to allow collapse of  one lung (while ventilating the other) for ease of  surgery . Their use is also essential to isola healthy lung in empyema and in the case of  a bronchopleural fistula. V entilating bronchoscopes and endobronchial catheters can be used to maintain oxygenation during laryngotracheal surgery or bronchoscopy by using intermittent jets of  oxygen. Arthur Ernest Guedel , 1883–1956, Clinical Professor of  Anesthesiology , University of  Southern California, Los Angeles, CA, USA. Techniques for maintaining an airway /uni25CF /uni25CF /uni25CF /uni25CF Summary box 23.6 Complications of intubation /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF
®
Figure 23.5
Airtraq
intubating device.
Figure 23.6
Fibreoptic intubating bronchoscope.
Chin lift and jaw thrust: suitable for the short term when no aid
is available
Guedel airway: holds the tongue forward but does not prevent
aspiration
Supraglottic device: easy insertion, reliable airway, allows
ventilation
Endotracheal intubation: secure and protected airway
Failed intubation
Accidental bronchial intubation
Trauma to teeth, pharynx or larynx
Aspiration of gastric contents during intubation
Disconnection, blockage or kinking of tube
Delayed tracheal stenosis
Management of the airway during anaesthesia
Loss of  muscle tone as a result of  general anaesthesia means that the patient can no longer keep their airway open. There fore, patients need their airway to be maintained for them. The use of  muscle relaxants will mean that they will also be unable to breathe for themselves and so will require artificial ventilation. Head tilt, chin lift and jaw thrust manoeuvr es along with adjuncts such as oropharyngeal airways ( Figure 23.2 used to facilitate bag–mask ventilation while induction agents exert their full e ff ect. A laryngeal mask airway or endotracheal tube is then inserted, and the patient is allowed to breathe spontaneously or is ventilated during the procedure. The addition of a cu ff to the endo-tracheal tube facilitates positive pressure ventilation and protects the lungs from aspi ration of  regurgitated gastric contents. Supraglottic airways /uni25CF Laryngeal mask airway (LMA) . Developed by Dr Archie Brain in the UK, the original LMA first-generation supraglottic airway . The mask with an inflatable cu ff is inserted via the mouth and produces a seal around the glottic opening, providing a very reliable means of  maintaining the airway . Its placement is less irritating and less traumatic to a patient’s airway than endotracheal intubation. The technique can be easily taught to non anaesthetists and paramedics and can be used as an emergency airway management tool. Several varieties of first-generation LMAs are available, including the classic LMA and the flexible LMA. Further advancements ha led to the development of  second-generation supraglottic ® devices, such as the ProSeal LMA and the i-gel ( Figure 23.3 ). These devices usually have an in-built ‘bite block’ and oesophageal drain tube. They can be used for ventilation of  the lungs at higher inflation pressures and are more suitable for patients with a higher body mass index. There are also modified versions of  the LMA, including the ILMA (intubating LMA), that allow a blind technique, aiding insertion of  a tracheal tube in di ffi cult conditions. Archie Brain , b. 1942, formally an anaesthetist, whose patent application for the laryngeal mask airway was granted in 1982. devices have a good safety and e ffi cacy profile and should be replacing all first-generation devices. /uni25CF Di ffi cult intubation . Endotracheal intubation is feasible in most patients, but in a certain proportion of patients it may be di ffi cult or impossible. However, if  it is compounded by an inability to ventilate and therefore maintain oxygenation of  the patient by bag–mask, the consequence can be catastrophic hypoxia. Many devices - have been developed to aid intubation if  di ffi culty is ® ® ® anticipated (e.g. McGrath blade, Airtraq , C-MAC video laryngoscope) ( Figures 23.4 and 23.5 ); similarly , protocols have been created by specialised societies to deal ) are - ® is a - ve ®
Figure 23.2
Oropharyngeal airways.
®
Figure 23.3
i-gel
supraglottic airway.
Figure 23.4
Single-use laryngoscope.
with such situations. One specialised method for intubation in di ffi cult situations is the use of the fibreoptic intubating bronchoscope ( Figure 23.6 ), facilitated by topical local anaesthetic in awake patients or using general anaesthesia. The anaesthetist places the endotracheal tube in the trachea by threading the tube over the bronchoscope, and so places the tube in the trachea under direct bronchoscopic vision. An awake intubation requires careful patient selection, as it may not be a suitable technique for all patient groups. Double-lumen tubes and endobronchial tubes are used in procedures such as thoracoscopic, pulmonary and oesophageal surgery to allow collapse of  one lung (while ventilating the other) for ease of  surgery . Their use is also essential to isola healthy lung in empyema and in the case of  a bronchopleural fistula. V entilating bronchoscopes and endobronchial catheters can be used to maintain oxygenation during laryngotracheal surgery or bronchoscopy by using intermittent jets of  oxygen. Arthur Ernest Guedel , 1883–1956, Clinical Professor of  Anesthesiology , University of  Southern California, Los Angeles, CA, USA. Techniques for maintaining an airway /uni25CF /uni25CF /uni25CF /uni25CF Summary box 23.6 Complications of intubation /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF
®
Figure 23.5
Airtraq
intubating device.
Figure 23.6
Fibreoptic intubating bronchoscope.
Chin lift and jaw thrust: suitable for the short term when no aid
is available
Guedel airway: holds the tongue forward but does not prevent
aspiration
Supraglottic device: easy insertion, reliable airway, allows
ventilation
Endotracheal intubation: secure and protected airway
Failed intubation
Accidental bronchial intubation
Trauma to teeth, pharynx or larynx
Aspiration of gastric contents during intubation
Disconnection, blockage or kinking of tube
Delayed tracheal stenosis

Monitoring and care during anaesthesia
Monitoring and care during anaesthesia
A minimum basic monitoring of  cardiovascular parameters is required during surgery . This includes: /uni25CF vascular /uni25CF electrocardiogram (ECG); /uni25CF blood pressure; /uni25CF adequacy of  ventilation: /uni25CF inspired oxygen concentration; /uni25CF oxygen saturation by pulse oximetry; /uni25CF end-tidal carbon dioxide concentration. Monitors of  temperature, ventilation parameters and delivery of  anaesthetic agents are also routinely used, while measurement of  urine output and central venous pressure are recommended for major surgery . Friedrich Trendelenburg , 1844–1924, successively Professor of  Surgery at Rostock (1875–1882), Bonn (1822–1895) and Leipzig (1895–1911), Germany . The Trendelenburg position was first described in 1885. /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF Summary box 23.7 - Intermittent positive-pressure ventilation /uni25CF /uni25CF ed - /uni25CF -
Disadvantages
Muscle pain, hyperkalaemia, prolonged apnoea and
life-threatening malignant hyperthermia
Dependent on hepatic metabolism and renal clearance;
hence, caution if hepatic and renal impairment
Histamine release and allergic reactions
Allergic reactions
Excreted unchanged via bile and urine
Volume controlled, which ensures adequate gas entry but
risks high-pressure damage
Pressure controlled, which avoids high-pressure damage but
risks inadequate ventilation
PEEP reduces alveolar collapse and reduces vascular
shunting so improving perfusion
Monitoring and care during anaesthesia
A minimum basic monitoring of  cardiovascular parameters is required during surgery . This includes: /uni25CF vascular /uni25CF electrocardiogram (ECG); /uni25CF blood pressure; /uni25CF adequacy of  ventilation: /uni25CF inspired oxygen concentration; /uni25CF oxygen saturation by pulse oximetry; /uni25CF end-tidal carbon dioxide concentration. Monitors of  temperature, ventilation parameters and delivery of  anaesthetic agents are also routinely used, while measurement of  urine output and central venous pressure are recommended for major surgery . Friedrich Trendelenburg , 1844–1924, successively Professor of  Surgery at Rostock (1875–1882), Bonn (1822–1895) and Leipzig (1895–1911), Germany . The Trendelenburg position was first described in 1885. /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF Summary box 23.7 - Intermittent positive-pressure ventilation /uni25CF /uni25CF ed - /uni25CF -
Disadvantages
Muscle pain, hyperkalaemia, prolonged apnoea and
life-threatening malignant hyperthermia
Dependent on hepatic metabolism and renal clearance;
hence, caution if hepatic and renal impairment
Histamine release and allergic reactions
Allergic reactions
Excreted unchanged via bile and urine
Volume controlled, which ensures adequate gas entry but
risks high-pressure damage
Pressure controlled, which avoids high-pressure damage but
risks inadequate ventilation
PEEP reduces alveolar collapse and reduces vascular
shunting so improving perfusion
Monitoring and care during anaesthesia
A minimum basic monitoring of  cardiovascular parameters is required during surgery . This includes: /uni25CF vascular /uni25CF electrocardiogram (ECG); /uni25CF blood pressure; /uni25CF adequacy of  ventilation: /uni25CF inspired oxygen concentration; /uni25CF oxygen saturation by pulse oximetry; /uni25CF end-tidal carbon dioxide concentration. Monitors of  temperature, ventilation parameters and delivery of  anaesthetic agents are also routinely used, while measurement of  urine output and central venous pressure are recommended for major surgery . Friedrich Trendelenburg , 1844–1924, successively Professor of  Surgery at Rostock (1875–1882), Bonn (1822–1895) and Leipzig (1895–1911), Germany . The Trendelenburg position was first described in 1885. /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF Summary box 23.7 - Intermittent positive-pressure ventilation /uni25CF /uni25CF ed - /uni25CF -
Disadvantages
Muscle pain, hyperkalaemia, prolonged apnoea and
life-threatening malignant hyperthermia
Dependent on hepatic metabolism and renal clearance;
hence, caution if hepatic and renal impairment
Histamine release and allergic reactions
Allergic reactions
Excreted unchanged via bile and urine
Volume controlled, which ensures adequate gas entry but
risks high-pressure damage
Pressure controlled, which avoids high-pressure damage but
risks inadequate ventilation
PEEP reduces alveolar collapse and reduces vascular
shunting so improving perfusion

Muscle relaxation and artificial ventilation
Muscle relaxation and artificial ventilation
Pharmacological blockade of  neuromuscular transmission by neuromuscular blocking agents provides relaxation of muscles, allowing easy surgical access. However, the patient will need artificial ventilation. Neuromuscular blocking agents are broadly classified into depolarising and non-depolarising groups according to their mode of  action ( Table 23.1 ). Suxamethonium is the most commonly used depolarising agent. It binds to the nicotinic acetylcholine receptors, result - ing in opening of  the cation channel, leading to depolarisation and rapid relaxation of  muscles. Despite its adv erse e ff ects such as hyperkalaemia, muscle pain, anaphylaxis and potentially life-threatening malignant hyperthermia, suxamethonium is still widely used because of its quick onset and short duration of  action. These properties are useful when rapid endotracheal intubation is necessary to protect the patient’s airway or when short duration surgery is performed. Non-depolarising muscle relaxants act by competitive blockade of  postsynaptic receptors at the neuromuscular junction. They provide longer, pr edictable activity but require careful monitoring, appropriate timing and reversal of their action by agents such as neostigmine and sugammadex at the end of  the procedure. A peripheral nerve stimulator is rou - tinely used to monitor the depth of  neuromuscular block and also to confirm satisfactory recovery of  muscle power prior to te the extubation. With the incr easing availability and evidence of the use of  sugammadex, the non-depolarising muscle relax - ant rocuronium is an alternative to suxamethonium in the ‘rapid-sequence’ induction as it allows reversal of  its actions with sugammadex in a rapid manner. /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF
Advantages
Suxamethonium
Quickest onset, very short duration, spontaneous
recovery
Ideal for rapid intubation and for short procedures
Vecuronium
Long acting
Minimal cardiovascular effect and less allergic reaction
Atracurium
Intermediate acting
Non-enzymatic Hofmann degradation
Suitable in renal and hepatic failure
Rocuronium
Rapid onset, intermediate action
Suitable for rapid intubation
Rapid reversal possible using sugammadex
Muscle relaxation and artificial ventilation
Pharmacological blockade of  neuromuscular transmission by neuromuscular blocking agents provides relaxation of muscles, allowing easy surgical access. However, the patient will need artificial ventilation. Neuromuscular blocking agents are broadly classified into depolarising and non-depolarising groups according to their mode of  action ( Table 23.1 ). Suxamethonium is the most commonly used depolarising agent. It binds to the nicotinic acetylcholine receptors, result - ing in opening of  the cation channel, leading to depolarisation and rapid relaxation of  muscles. Despite its adv erse e ff ects such as hyperkalaemia, muscle pain, anaphylaxis and potentially life-threatening malignant hyperthermia, suxamethonium is still widely used because of its quick onset and short duration of  action. These properties are useful when rapid endotracheal intubation is necessary to protect the patient’s airway or when short duration surgery is performed. Non-depolarising muscle relaxants act by competitive blockade of  postsynaptic receptors at the neuromuscular junction. They provide longer, pr edictable activity but require careful monitoring, appropriate timing and reversal of their action by agents such as neostigmine and sugammadex at the end of  the procedure. A peripheral nerve stimulator is rou - tinely used to monitor the depth of  neuromuscular block and also to confirm satisfactory recovery of  muscle power prior to te the extubation. With the incr easing availability and evidence of the use of  sugammadex, the non-depolarising muscle relax - ant rocuronium is an alternative to suxamethonium in the ‘rapid-sequence’ induction as it allows reversal of  its actions with sugammadex in a rapid manner. /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF
Advantages
Suxamethonium
Quickest onset, very short duration, spontaneous
recovery
Ideal for rapid intubation and for short procedures
Vecuronium
Long acting
Minimal cardiovascular effect and less allergic reaction
Atracurium
Intermediate acting
Non-enzymatic Hofmann degradation
Suitable in renal and hepatic failure
Rocuronium
Rapid onset, intermediate action
Suitable for rapid intubation
Rapid reversal possible using sugammadex
Muscle relaxation and artificial ventilation
Pharmacological blockade of  neuromuscular transmission by neuromuscular blocking agents provides relaxation of muscles, allowing easy surgical access. However, the patient will need artificial ventilation. Neuromuscular blocking agents are broadly classified into depolarising and non-depolarising groups according to their mode of  action ( Table 23.1 ). Suxamethonium is the most commonly used depolarising agent. It binds to the nicotinic acetylcholine receptors, result - ing in opening of  the cation channel, leading to depolarisation and rapid relaxation of  muscles. Despite its adv erse e ff ects such as hyperkalaemia, muscle pain, anaphylaxis and potentially life-threatening malignant hyperthermia, suxamethonium is still widely used because of its quick onset and short duration of  action. These properties are useful when rapid endotracheal intubation is necessary to protect the patient’s airway or when short duration surgery is performed. Non-depolarising muscle relaxants act by competitive blockade of  postsynaptic receptors at the neuromuscular junction. They provide longer, pr edictable activity but require careful monitoring, appropriate timing and reversal of their action by agents such as neostigmine and sugammadex at the end of  the procedure. A peripheral nerve stimulator is rou - tinely used to monitor the depth of  neuromuscular block and also to confirm satisfactory recovery of  muscle power prior to te the extubation. With the incr easing availability and evidence of the use of  sugammadex, the non-depolarising muscle relax - ant rocuronium is an alternative to suxamethonium in the ‘rapid-sequence’ induction as it allows reversal of  its actions with sugammadex in a rapid manner. /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF
Advantages
Suxamethonium
Quickest onset, very short duration, spontaneous
recovery
Ideal for rapid intubation and for short procedures
Vecuronium
Long acting
Minimal cardiovascular effect and less allergic reaction
Atracurium
Intermediate acting
Non-enzymatic Hofmann degradation
Suitable in renal and hepatic failure
Rocuronium
Rapid onset, intermediate action
Suitable for rapid intubation
Rapid reversal possible using sugammadex

PAIN
PAIN
Pain is defined as ‘ An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage.’ Most patients will experience pain after surgery . This is usually managed by a combination of  painkillers and local anaesthetic techniques (multimodal analgesia). The common painkillers that are used are regular paracetamol, non-steroidal anti-inflammatory drugs (NSAIDs) and opioids. Opioids can be weak, such as codeine, or stronger opioids, such as morphine and oxycodone. Opioids are associated with a high incidence of  side e ff ects (nausea and vomiting, respiratory depression, itching). By combining opioids with other drugs, the dose of  opioid can be minimised, thus side e ff ects can be reduced. - PAIN
Pain is defined as ‘ An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage.’ Most patients will experience pain after surgery . This is usually managed by a combination of  painkillers and local anaesthetic techniques (multimodal analgesia). The common painkillers that are used are regular paracetamol, non-steroidal anti-inflammatory drugs (NSAIDs) and opioids. Opioids can be weak, such as codeine, or stronger opioids, such as morphine and oxycodone. Opioids are associated with a high incidence of  side e ff ects (nausea and vomiting, respiratory depression, itching). By combining opioids with other drugs, the dose of  opioid can be minimised, thus side e ff ects can be reduced. - PAIN
Pain is defined as ‘ An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage.’ Most patients will experience pain after surgery . This is usually managed by a combination of  painkillers and local anaesthetic techniques (multimodal analgesia). The common painkillers that are used are regular paracetamol, non-steroidal anti-inflammatory drugs (NSAIDs) and opioids. Opioids can be weak, such as codeine, or stronger opioids, such as morphine and oxycodone. Opioids are associated with a high incidence of  side e ff ects (nausea and vomiting, respiratory depression, itching). By combining opioids with other drugs, the dose of  opioid can be minimised, thus side e ff ects can be reduced. -

PREPARATION FOR ANAESTHESIA
PREPARATION FOR ANAESTHESIA
A surgeon’s role is to carry out, in cooperation with the anaes - thetist, a thorough preoperative assessment that recognises medical and anaesthetic risk factors and facilitates the optimi - sation of  the patient’s condition (see Chapter 21 ). An Universal Etymological English Dictionary in 1751. , while working with Harold Gillies (pioneer of plastic surgery), developed tracheal intu - standardised care pathway with a carefully chosen anaesthetic and analgesic technique is the cornerstone of  the ‘enhanced recovery programmes’ that have been introduced recently across the surgical specialties. PREPARATION FOR ANAESTHESIA
A surgeon’s role is to carry out, in cooperation with the anaes - thetist, a thorough preoperative assessment that recognises medical and anaesthetic risk factors and facilitates the optimi - sation of  the patient’s condition (see Chapter 21 ). An Universal Etymological English Dictionary in 1751. , while working with Harold Gillies (pioneer of plastic surgery), developed tracheal intu - standardised care pathway with a carefully chosen anaesthetic and analgesic technique is the cornerstone of  the ‘enhanced recovery programmes’ that have been introduced recently across the surgical specialties. PREPARATION FOR ANAESTHESIA
A surgeon’s role is to carry out, in cooperation with the anaes - thetist, a thorough preoperative assessment that recognises medical and anaesthetic risk factors and facilitates the optimi - sation of  the patient’s condition (see Chapter 21 ). An Universal Etymological English Dictionary in 1751. , while working with Harold Gillies (pioneer of plastic surgery), developed tracheal intu - standardised care pathway with a carefully chosen anaesthetic and analgesic technique is the cornerstone of  the ‘enhanced recovery programmes’ that have been introduced recently across the surgical specialties.

Pain control in malignant disease
Pain control in malignant disease
Pain is a common symptom associated with cancer, even more so during the advanced stages. In intractable pain, the under lying principle of  treatment is to encourage independence of the patient and an active life in spite of  the symptom. WHO advises use of  the ‘WHO analgesic ladder’: /uni25CF first step: simple analgesics – paracetamol, NSAIDs, tricy clic drugs or anticonvulsant drugs; /uni25CF second step: intermediate-strength opioids – codeine, tra madol; /uni25CF third step: strong opioids – morphine (pethidine has now been withdrawn). Oral opiate analgesia is necessary when the less power ful analgesic agents no longer control pain on movement or enable the patient to sleep. Opioids may exhibit both depen dence and addiction with long-term use. It is important to dis tinguish between addiction and dependence; the f ormer is a psychosocial phenomenon whereas the latter is a purely phys iological response to a given drug. Some patients experience ‘breakthrough pain’ (acute, e xcruciating and incapacitating), which occurs either spontaneously or in relation to a specific predictable or unpredictable trig ger experienced by patients who have relatively stable and adequately controlled back ground pain. Opioid rotation or switching may be considered if  a patient obtains pain relief  with one opioid and has severe adverse e ff ects. Oral morphine, which is often used for chronic pain, can be pr escribed in short-acting liquid or tablet form and should be administered regularly every 4 hours until an adequate dose of  drug has been titrated to control the pain over 24 hour Once this is established, the daily dose can be divided into - - - two separate administrations of  enteric-coated, slow-release morphine tablets (MST morphine) every 12 hours. Additional short-acting opioids (morphine/fentanyl) can then be used to - cover episodes of  ‘breakthrough pain’. Nausea treated using antiemetic agents does not usually persist, but constipation is - a frequent and persistent complication requiring regular pre - vention by laxatives. Infusion of subcutaneous, intravenous, - intrathecal or epidural opiate drugs The infusion of  an opiate is necessary if  a patient is unable - to take oral drugs. Subcutaneous infusion of  diamorphine - is e ff ective and simple to administer. Epidural infusions of diamorphine with an external pump can be used in mobile - patients. Intrathecal infusions with pumps programmed by external computers are used; however, there is a possibility of the patient developing an infection with catastrophic e ff ects. Intravenous narcotic agents may be reserved for acute crises, such as pathological fractures. - Neurolytic techniques in cancer pain These should only be used if  life expectancy is limited and the diagnosis is certain. The useful procedures are: /uni25CF subcostal phenol injection for a rib metastasis; /uni25CF coeliac plexus neurolytic block with alcohol for the pain caused by pancreatic, gastric or hepatic cancer; s. /uni25CF intrathecal neurolytic injection of  hyperbaric phenol;
Figure 23.9
Dual-lead spinal cord stimulator in the epidural space.
spinothalamic ascending pain pathway; this is a highly e ff ective technique in experienced hands, selectively eliminating pain and temperature sensation in a specific limited area. Alternative strategies include: /uni25CF the development of  anti-pituitary hormone drugs, such as tamoxifen and cyproterone, has enabled e ff ective pharma cological therapy for the pain of  widespread metastases instead of  pituitary ablation surgery; /uni25CF palliative radiotherapy can be most beneficial for the relief  of  pain in metastatic disease; adjuvant drugs such as corticosteroids to reduce cerebral oedema or inflammation around a tumour, which may be useful in symptom control; tricyclic antidepressants, anticonvulsants and flecainide are also used to reduce the pain of  nerve injury . Summary box 23.11 Approximate equianalgesic potencies of opioids for oral administration Chou R, Gordon DB, de Leon-Casasola OA et al . Management of postoperative pain: a clinical practice guideline from the American Pain Society , the American Society of  Regional Anesthesia and Pain Medicine, and the American Society of  Anesthesiologists’ Committee on Regional Anesthesia, Executive Committee, and Administrative Council. J Pain 2016; 17 (2): 131–57. Dansie EJ, Turk DC. Assessment of  patients with chronic pain. Br J Anaesth 2013; 111 (1): 19–25. - Frerk C, Mitchell VS, McNarry AF et al . Di ffi cult Airway Society 2015 guidelines for management of unanticipated di ffi cult intubation in adults. Br J Anaesth 2015; 115 (6): 827–48. McLeod GA, McCartney CGL, Wildsmith JAW . Wildsmith and Armitage’s principles and practice of  regional anaesthesia , 4th edn. Oxford: Oxford University Press, 2012. Rawal N (ed.). Management of  acute and chronic pain . London: BMJ Books, 1998. Sneyd JR. Recent advances in intravenous anaesthesia. Br J Anaesth 2004; 93 (5): 725–36. Thompson J, Moppett I, Wiles M. Smith and Aitkenhead’s textbook of anaesthesia , 7th edn. Edinburgh: Elsevier, 2019.
Potency Equivalent dose to
10
/uni00A0
mg oral morphine
Codeine phosphate 0.1 100
/uni00A0
mg
Dihydrocodeine 0.1 100
/uni00A0
mg
Hydromorphone 5
2
/uni00A0
mg
Morphine
1
10
/uni00A0
mg
Oxycodone
1.5 6.6
/uni00A0
mg
Tapentadol
0.4 100
/uni00A0
mg
Adapted from the British National Formulary.
Pain control in malignant disease
Pain is a common symptom associated with cancer, even more so during the advanced stages. In intractable pain, the under lying principle of  treatment is to encourage independence of the patient and an active life in spite of  the symptom. WHO advises use of  the ‘WHO analgesic ladder’: /uni25CF first step: simple analgesics – paracetamol, NSAIDs, tricy clic drugs or anticonvulsant drugs; /uni25CF second step: intermediate-strength opioids – codeine, tra madol; /uni25CF third step: strong opioids – morphine (pethidine has now been withdrawn). Oral opiate analgesia is necessary when the less power ful analgesic agents no longer control pain on movement or enable the patient to sleep. Opioids may exhibit both depen dence and addiction with long-term use. It is important to dis tinguish between addiction and dependence; the f ormer is a psychosocial phenomenon whereas the latter is a purely phys iological response to a given drug. Some patients experience ‘breakthrough pain’ (acute, e xcruciating and incapacitating), which occurs either spontaneously or in relation to a specific predictable or unpredictable trig ger experienced by patients who have relatively stable and adequately controlled back ground pain. Opioid rotation or switching may be considered if  a patient obtains pain relief  with one opioid and has severe adverse e ff ects. Oral morphine, which is often used for chronic pain, can be pr escribed in short-acting liquid or tablet form and should be administered regularly every 4 hours until an adequate dose of  drug has been titrated to control the pain over 24 hour Once this is established, the daily dose can be divided into - - - two separate administrations of  enteric-coated, slow-release morphine tablets (MST morphine) every 12 hours. Additional short-acting opioids (morphine/fentanyl) can then be used to - cover episodes of  ‘breakthrough pain’. Nausea treated using antiemetic agents does not usually persist, but constipation is - a frequent and persistent complication requiring regular pre - vention by laxatives. Infusion of subcutaneous, intravenous, - intrathecal or epidural opiate drugs The infusion of  an opiate is necessary if  a patient is unable - to take oral drugs. Subcutaneous infusion of  diamorphine - is e ff ective and simple to administer. Epidural infusions of diamorphine with an external pump can be used in mobile - patients. Intrathecal infusions with pumps programmed by external computers are used; however, there is a possibility of the patient developing an infection with catastrophic e ff ects. Intravenous narcotic agents may be reserved for acute crises, such as pathological fractures. - Neurolytic techniques in cancer pain These should only be used if  life expectancy is limited and the diagnosis is certain. The useful procedures are: /uni25CF subcostal phenol injection for a rib metastasis; /uni25CF coeliac plexus neurolytic block with alcohol for the pain caused by pancreatic, gastric or hepatic cancer; s. /uni25CF intrathecal neurolytic injection of  hyperbaric phenol;
Figure 23.9
Dual-lead spinal cord stimulator in the epidural space.
spinothalamic ascending pain pathway; this is a highly e ff ective technique in experienced hands, selectively eliminating pain and temperature sensation in a specific limited area. Alternative strategies include: /uni25CF the development of  anti-pituitary hormone drugs, such as tamoxifen and cyproterone, has enabled e ff ective pharma cological therapy for the pain of  widespread metastases instead of  pituitary ablation surgery; /uni25CF palliative radiotherapy can be most beneficial for the relief  of  pain in metastatic disease; adjuvant drugs such as corticosteroids to reduce cerebral oedema or inflammation around a tumour, which may be useful in symptom control; tricyclic antidepressants, anticonvulsants and flecainide are also used to reduce the pain of  nerve injury . Summary box 23.11 Approximate equianalgesic potencies of opioids for oral administration Chou R, Gordon DB, de Leon-Casasola OA et al . Management of postoperative pain: a clinical practice guideline from the American Pain Society , the American Society of  Regional Anesthesia and Pain Medicine, and the American Society of  Anesthesiologists’ Committee on Regional Anesthesia, Executive Committee, and Administrative Council. J Pain 2016; 17 (2): 131–57. Dansie EJ, Turk DC. Assessment of  patients with chronic pain. Br J Anaesth 2013; 111 (1): 19–25. - Frerk C, Mitchell VS, McNarry AF et al . Di ffi cult Airway Society 2015 guidelines for management of unanticipated di ffi cult intubation in adults. Br J Anaesth 2015; 115 (6): 827–48. McLeod GA, McCartney CGL, Wildsmith JAW . Wildsmith and Armitage’s principles and practice of  regional anaesthesia , 4th edn. Oxford: Oxford University Press, 2012. Rawal N (ed.). Management of  acute and chronic pain . London: BMJ Books, 1998. Sneyd JR. Recent advances in intravenous anaesthesia. Br J Anaesth 2004; 93 (5): 725–36. Thompson J, Moppett I, Wiles M. Smith and Aitkenhead’s textbook of anaesthesia , 7th edn. Edinburgh: Elsevier, 2019.
Potency Equivalent dose to
10
/uni00A0
mg oral morphine
Codeine phosphate 0.1 100
/uni00A0
mg
Dihydrocodeine 0.1 100
/uni00A0
mg
Hydromorphone 5
2
/uni00A0
mg
Morphine
1
10
/uni00A0
mg
Oxycodone
1.5 6.6
/uni00A0
mg
Tapentadol
0.4 100
/uni00A0
mg
Adapted from the British National Formulary.
Pain control in malignant disease
Pain is a common symptom associated with cancer, even more so during the advanced stages. In intractable pain, the under lying principle of  treatment is to encourage independence of the patient and an active life in spite of  the symptom. WHO advises use of  the ‘WHO analgesic ladder’: /uni25CF first step: simple analgesics – paracetamol, NSAIDs, tricy clic drugs or anticonvulsant drugs; /uni25CF second step: intermediate-strength opioids – codeine, tra madol; /uni25CF third step: strong opioids – morphine (pethidine has now been withdrawn). Oral opiate analgesia is necessary when the less power ful analgesic agents no longer control pain on movement or enable the patient to sleep. Opioids may exhibit both depen dence and addiction with long-term use. It is important to dis tinguish between addiction and dependence; the f ormer is a psychosocial phenomenon whereas the latter is a purely phys iological response to a given drug. Some patients experience ‘breakthrough pain’ (acute, e xcruciating and incapacitating), which occurs either spontaneously or in relation to a specific predictable or unpredictable trig ger experienced by patients who have relatively stable and adequately controlled back ground pain. Opioid rotation or switching may be considered if  a patient obtains pain relief  with one opioid and has severe adverse e ff ects. Oral morphine, which is often used for chronic pain, can be pr escribed in short-acting liquid or tablet form and should be administered regularly every 4 hours until an adequate dose of  drug has been titrated to control the pain over 24 hour Once this is established, the daily dose can be divided into - - - two separate administrations of  enteric-coated, slow-release morphine tablets (MST morphine) every 12 hours. Additional short-acting opioids (morphine/fentanyl) can then be used to - cover episodes of  ‘breakthrough pain’. Nausea treated using antiemetic agents does not usually persist, but constipation is - a frequent and persistent complication requiring regular pre - vention by laxatives. Infusion of subcutaneous, intravenous, - intrathecal or epidural opiate drugs The infusion of  an opiate is necessary if  a patient is unable - to take oral drugs. Subcutaneous infusion of  diamorphine - is e ff ective and simple to administer. Epidural infusions of diamorphine with an external pump can be used in mobile - patients. Intrathecal infusions with pumps programmed by external computers are used; however, there is a possibility of the patient developing an infection with catastrophic e ff ects. Intravenous narcotic agents may be reserved for acute crises, such as pathological fractures. - Neurolytic techniques in cancer pain These should only be used if  life expectancy is limited and the diagnosis is certain. The useful procedures are: /uni25CF subcostal phenol injection for a rib metastasis; /uni25CF coeliac plexus neurolytic block with alcohol for the pain caused by pancreatic, gastric or hepatic cancer; s. /uni25CF intrathecal neurolytic injection of  hyperbaric phenol;
Figure 23.9
Dual-lead spinal cord stimulator in the epidural space.
spinothalamic ascending pain pathway; this is a highly e ff ective technique in experienced hands, selectively eliminating pain and temperature sensation in a specific limited area. Alternative strategies include: /uni25CF the development of  anti-pituitary hormone drugs, such as tamoxifen and cyproterone, has enabled e ff ective pharma cological therapy for the pain of  widespread metastases instead of  pituitary ablation surgery; /uni25CF palliative radiotherapy can be most beneficial for the relief  of  pain in metastatic disease; adjuvant drugs such as corticosteroids to reduce cerebral oedema or inflammation around a tumour, which may be useful in symptom control; tricyclic antidepressants, anticonvulsants and flecainide are also used to reduce the pain of  nerve injury . Summary box 23.11 Approximate equianalgesic potencies of opioids for oral administration Chou R, Gordon DB, de Leon-Casasola OA et al . Management of postoperative pain: a clinical practice guideline from the American Pain Society , the American Society of  Regional Anesthesia and Pain Medicine, and the American Society of  Anesthesiologists’ Committee on Regional Anesthesia, Executive Committee, and Administrative Council. J Pain 2016; 17 (2): 131–57. Dansie EJ, Turk DC. Assessment of  patients with chronic pain. Br J Anaesth 2013; 111 (1): 19–25. - Frerk C, Mitchell VS, McNarry AF et al . Di ffi cult Airway Society 2015 guidelines for management of unanticipated di ffi cult intubation in adults. Br J Anaesth 2015; 115 (6): 827–48. McLeod GA, McCartney CGL, Wildsmith JAW . Wildsmith and Armitage’s principles and practice of  regional anaesthesia , 4th edn. Oxford: Oxford University Press, 2012. Rawal N (ed.). Management of  acute and chronic pain . London: BMJ Books, 1998. Sneyd JR. Recent advances in intravenous anaesthesia. Br J Anaesth 2004; 93 (5): 725–36. Thompson J, Moppett I, Wiles M. Smith and Aitkenhead’s textbook of anaesthesia , 7th edn. Edinburgh: Elsevier, 2019.
Potency Equivalent dose to
10
/uni00A0
mg oral morphine
Codeine phosphate 0.1 100
/uni00A0
mg
Dihydrocodeine 0.1 100
/uni00A0
mg
Hydromorphone 5
2
/uni00A0
mg
Morphine
1
10
/uni00A0
mg
Oxycodone
1.5 6.6
/uni00A0
mg
Tapentadol
0.4 100
/uni00A0
mg
Adapted from the British National Formulary.

Paracetamol and non-steroidal anti - inflammatory d
Paracetamol and non-steroidal anti - inflammatory drugs
Paracetamol was first synthesised in 1878 by Morse and was - introduced for medical usage in 1883. However, because of misinterpretation of  its safety profile, its use was limited until the 1950s, when the chemically similar, and until then preferred analgesic, phenacetin was withdrawn owing to renal toxicity . Paracetamol is probably now the most commonly used drug worldwide; it is available over the counter, used in almost all ages and forms step 1 of  the WHO analgesic ladder. It is first - line treatment for pyrexia and pain, plays an important role in multimodal analgesia and is considered to possess a generally excellent safety profile, except in significant overdose, with only a few drug interactions. Oral and rectal administration can pr oduce analgesia within 40 minutes, with maximal e ff ect at range 63–89% for oral and 24–98% for rectally administered preparations) the timing of onset can be unpredictable. The introduction of  its intravenously administered preparation within the last decade overcomes this issue. NSAIDs are used in the treatment of  acute pain for their opioid-sparing e ff ects, as part of a multimodal analgesic reg imen. However, it is important to r ecognise that long-term usage and an increase in prescription may be associated with significant morbidities. Increased risk of perioperative bleed ing, g astrointestinal bleeding and ulceration, thrombotic events such as myocardial infarction and stroke, renal impairment, fluid retention and exacerbation of  asthma are some of  the side e ff ects of  NSAIDs, sug gesting cautious usage. Intravenous opioids administered as patient-controlled analgesia (PCA) for pain relief  is a useful technique. The patient is trained to give a bolus dose of  drug by pressing a control button on a machine, the functions of  whic h have been regulated by medical sta ff . The strength, frequency and total dose of  drug in a given time are all limited by computer. This method is popular with patients as they have control and pre vents delays in administration of  doses. Paracetamol and non-steroidal anti - inflammatory drugs
Paracetamol was first synthesised in 1878 by Morse and was - introduced for medical usage in 1883. However, because of misinterpretation of  its safety profile, its use was limited until the 1950s, when the chemically similar, and until then preferred analgesic, phenacetin was withdrawn owing to renal toxicity . Paracetamol is probably now the most commonly used drug worldwide; it is available over the counter, used in almost all ages and forms step 1 of  the WHO analgesic ladder. It is first - line treatment for pyrexia and pain, plays an important role in multimodal analgesia and is considered to possess a generally excellent safety profile, except in significant overdose, with only a few drug interactions. Oral and rectal administration can pr oduce analgesia within 40 minutes, with maximal e ff ect at range 63–89% for oral and 24–98% for rectally administered preparations) the timing of onset can be unpredictable. The introduction of  its intravenously administered preparation within the last decade overcomes this issue. NSAIDs are used in the treatment of  acute pain for their opioid-sparing e ff ects, as part of a multimodal analgesic reg imen. However, it is important to r ecognise that long-term usage and an increase in prescription may be associated with significant morbidities. Increased risk of perioperative bleed ing, g astrointestinal bleeding and ulceration, thrombotic events such as myocardial infarction and stroke, renal impairment, fluid retention and exacerbation of  asthma are some of  the side e ff ects of  NSAIDs, sug gesting cautious usage. Intravenous opioids administered as patient-controlled analgesia (PCA) for pain relief  is a useful technique. The patient is trained to give a bolus dose of  drug by pressing a control button on a machine, the functions of  whic h have been regulated by medical sta ff . The strength, frequency and total dose of  drug in a given time are all limited by computer. This method is popular with patients as they have control and pre vents delays in administration of  doses.

Paracetamol and non-steroidal anti - inflammatory drugs
Paracetamol and non-steroidal anti - inflammatory drugs
Paracetamol was first synthesised in 1878 by Morse and was - introduced for medical usage in 1883. However, because of misinterpretation of  its safety profile, its use was limited until the 1950s, when the chemically similar, and until then preferred analgesic, phenacetin was withdrawn owing to renal toxicity . Paracetamol is probably now the most commonly used drug worldwide; it is available over the counter, used in almost all ages and forms step 1 of  the WHO analgesic ladder. It is first - line treatment for pyrexia and pain, plays an important role in multimodal analgesia and is considered to possess a generally excellent safety profile, except in significant overdose, with only a few drug interactions. Oral and rectal administration can pr oduce analgesia within 40 minutes, with maximal e ff ect at range 63–89% for oral and 24–98% for rectally administered preparations) the timing of onset can be unpredictable. The introduction of  its intravenously administered preparation within the last decade overcomes this issue. NSAIDs are used in the treatment of  acute pain for their opioid-sparing e ff ects, as part of a multimodal analgesic reg imen. However, it is important to r ecognise that long-term usage and an increase in prescription may be associated with significant morbidities. Increased risk of perioperative bleed ing, g astrointestinal bleeding and ulceration, thrombotic events such as myocardial infarction and stroke, renal impairment, fluid retention and exacerbation of  asthma are some of  the side e ff ects of  NSAIDs, sug gesting cautious usage. Intravenous opioids administered as patient-controlled analgesia (PCA) for pain relief  is a useful technique. The patient is trained to give a bolus dose of  drug by pressing a control button on a machine, the functions of  whic h have been regulated by medical sta ff . The strength, frequency and total dose of  drug in a given time are all limited by computer. This method is popular with patients as they have control and pre vents delays in administration of  doses.

Principles of chronic pain management
Principles of chronic pain management
Non-pharmacological treatment This involves a multidisciplinary approach targeting the biopsychosocial model of  health ( Figure 23.8 ). Early assess - ment and engagement with physiotherapy and exercise are key contributors in successful management. Psychological inter - ventions such as counselling, cognitive behaviour therapy and mindfulness are recognised strategies for pain control. ‘Pain management prog rammes’ lay out a logical structure for this. - Pharmacological treatment Drugs in chronic non-malignant pain Paracetamol and NSAIDs are the mainstays of  musculoskel - etal pain treatment. The tricyclic antidepressant drugs and anticonvulsant agents are often useful for the pain of  nerve injury , although side e ff ects can prove troublesome and reduce compliance. Both pregabalin and gabapentin r educe sponta - neous neuronal activity by their action on the α δ subunit of  the 2 calcium channel. They are now routinely used for managing - neuropathic chronic pain. In more severe and debilitating non-malignant chronic pain, opioid analgesic drugs are used in slow release oral preparations (morphine and oxycodone) and transcutaneous patches (fentanyl and buprenorphine). - - - s - -
Physical
Genetic
health
vulnerabilities
Biological
Disability
Drug
Temperament
effects
IQ
Mental
Peers
Social skills
health
Social
Psychological
Family
relationships
Coping skills
School
Trauma
Family
circumstances
Self-esteem
Figure 23.8
Biopsychosocial model of health.
Commonly used terms in chronic pain Tapentadol, with its dual action on the opioid and noradren aline (norepinephrine) selective reuptake inhibition pathway , may provide relief  in patients with both a neuropathic and nociceptive element to their pain. Combinations of  drugs often prove useful to achie ve the optimum of  e ffi cacy with minimal side e ff ects. Treatment of pain dependent on sympathetic nervous system activity Even minor trauma and surgery (often of  a limb) can provoke excessive sympathetic adrenergic activity , inducing vasocon striction and abnormal nociceptive transmission. This can lead to chronic burning pain, allodynia, trophic changes and resultant disuse. Management includes antineuropathic pain medications - (pregabalin, gabapentin, amitriptyline) as part of  m ultimodal analgesia with a multidisciplinary pain management approach. This includes considerab le input from psychological services and targeted physiotherapy . Interventional treatment may include local anaesthetic injection of  the stellate ganglion for upper limb symptoms. Percutaneous chemical lumbar sympa - thectomy with local anaesthetic is used for relief  of  rest pain in advanced ischaemic disease of  the legs. Interventional pain management for chronic pain - Local anaesthetic and steroid injections can be e ff ective around an inflamed nerve and they reduce the cycle of constant pain transmission with consequent muscle spasm. Transforaminal
Term
De
/f_i
nition
Allodynia
Pain due to a stimulus that does not normally provoke pain. Allodynia involves a change in the quality
of a sensation, whether tactile, thermal or of any other sort
Analgesia
Absence of pain in response to stimulation that would normally be painful
Central sensitisation Increased responsiveness of nociceptive neurones in the central nervous system to their normal or
subthreshold afferent input. The net effect is that innocuous stimuli will be interpreted as painful
Epidural space
The space (or potential space) between the ligamentum
/f_l
avum (or vertebral wall) and the dura, just
outside the spinal canal, extending from the foramen magnum to the sacrum. Leads and catheters may
be placed in this space via a needle
Hyperalgesia
Abnormally heightened sensitivity to pain. For pain evoked by stimuli that usually are not painful, the
term allodynia is preferred, while hyperalgesia is more appropriately used for cases with an increased
response at a normal threshold or at an increased threshold
Hypoalgesia
Decreased sensitivity to painful stimuli. Hypoalgesia can be caused by exogenous chemicals such
as opioids, as well as by chemicals produced by the body in phenomena such as fear- and exercise-
induced hypoalgesia
Intrathecal space
The cerebrospinal
/f_l
uid-
/f_i
lled space around the spinal cord, protected by the dura mater, into which
certain medicines may be delivered to achieve their most potent effect
Nociception
Sensory response to certain harmful or potentially harmful stimuli. Nociception triggers a variety of
biological and behavioural responses and may also result in a subjective experience of pain
Neuropathic pain
Neuropathic pain is de
/f_i
ned as pain caused by a lesion or disease of the somatosensory nervous
system
Nociceptive pain
Pain that arises from actual or threatened damage to non-neural tissue and that is due to the activation
of nociceptors
Noxious stimulus
An actual or potential tissue-damaging event
Off-label
When a prescription drug is prescribed for uses other than what Australia’s Therapeutic Goods
Administration, the USA’s Food and Drug Administration or the UK’s Medicines and Healthcare
products Regulatory Agency has approved and published in the drug’s package insert
Pain
An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or
described in terms of such damage
Pain threshold
The minimum amount of a stimulus with which pain begins to be felt. It is an entirely subjective
phenomenon
Paraesthesia
Abnormal cutaneous sensations such as tingling, tickling, pricking or burning with no apparent physical
cause. Often described as ‘pins and needles’ or of a limb ‘falling asleep’
Peripheral neuropathic pain Pain caused by a lesion or disease of the peripheral somatosensory nervous system
of  nerve root irritation associated with or without minor disc prolapse, followed by active physiotherapy and rehabilitation to promote mobility . Nerve stimulation procedures such as acupuncture and transcutaneous nerve stimulation increase endorphin produc tion in the central nervous system. Nerve decompression cra niotomy rather than percutaneous coagulation of the ganglion is now performed for trigeminal neuralgia. Spinal cord stimulation (SCS) by dorsal column stimulation is now a recognised and e ff ective management of  intractable neuropa thic pain ( Figure 23.9 ). This involves placement of electrodes in the posterior epidural space to allow dorsal column stimulation through an implantable pulse generator inserted in the body . In the UK this has been recommended by National Institute for Health and Care Excellence (NICE) guidance for intractable neuropathic pain management. Robust evidence exists for its clinical and health economic benefit in failed back surgery syndrome, in which patients have undergone previous spinal surgery . Early use of  SCS in surgery-naive patients might lead to better outcomes. National guidelines in the UK do not recommend disc replacements or spinal fusions in patients with lower back pain unless the latter are part of  a trial, rendering a large part of  the patient population ineligible for surgery . In these instances, SCS could prove to be an e ff ective solution. Principles of chronic pain management
Non-pharmacological treatment This involves a multidisciplinary approach targeting the biopsychosocial model of  health ( Figure 23.8 ). Early assess - ment and engagement with physiotherapy and exercise are key contributors in successful management. Psychological inter - ventions such as counselling, cognitive behaviour therapy and mindfulness are recognised strategies for pain control. ‘Pain management prog rammes’ lay out a logical structure for this. - Pharmacological treatment Drugs in chronic non-malignant pain Paracetamol and NSAIDs are the mainstays of  musculoskel - etal pain treatment. The tricyclic antidepressant drugs and anticonvulsant agents are often useful for the pain of  nerve injury , although side e ff ects can prove troublesome and reduce compliance. Both pregabalin and gabapentin r educe sponta - neous neuronal activity by their action on the α δ subunit of  the 2 calcium channel. They are now routinely used for managing - neuropathic chronic pain. In more severe and debilitating non-malignant chronic pain, opioid analgesic drugs are used in slow release oral preparations (morphine and oxycodone) and transcutaneous patches (fentanyl and buprenorphine). - - - s - -
Physical
Genetic
health
vulnerabilities
Biological
Disability
Drug
Temperament
effects
IQ
Mental
Peers
Social skills
health
Social
Psychological
Family
relationships
Coping skills
School
Trauma
Family
circumstances
Self-esteem
Figure 23.8
Biopsychosocial model of health.
Commonly used terms in chronic pain Tapentadol, with its dual action on the opioid and noradren aline (norepinephrine) selective reuptake inhibition pathway , may provide relief  in patients with both a neuropathic and nociceptive element to their pain. Combinations of  drugs often prove useful to achie ve the optimum of  e ffi cacy with minimal side e ff ects. Treatment of pain dependent on sympathetic nervous system activity Even minor trauma and surgery (often of  a limb) can provoke excessive sympathetic adrenergic activity , inducing vasocon striction and abnormal nociceptive transmission. This can lead to chronic burning pain, allodynia, trophic changes and resultant disuse. Management includes antineuropathic pain medications - (pregabalin, gabapentin, amitriptyline) as part of  m ultimodal analgesia with a multidisciplinary pain management approach. This includes considerab le input from psychological services and targeted physiotherapy . Interventional treatment may include local anaesthetic injection of  the stellate ganglion for upper limb symptoms. Percutaneous chemical lumbar sympa - thectomy with local anaesthetic is used for relief  of  rest pain in advanced ischaemic disease of  the legs. Interventional pain management for chronic pain - Local anaesthetic and steroid injections can be e ff ective around an inflamed nerve and they reduce the cycle of constant pain transmission with consequent muscle spasm. Transforaminal
Term
De
/f_i
nition
Allodynia
Pain due to a stimulus that does not normally provoke pain. Allodynia involves a change in the quality
of a sensation, whether tactile, thermal or of any other sort
Analgesia
Absence of pain in response to stimulation that would normally be painful
Central sensitisation Increased responsiveness of nociceptive neurones in the central nervous system to their normal or
subthreshold afferent input. The net effect is that innocuous stimuli will be interpreted as painful
Epidural space
The space (or potential space) between the ligamentum
/f_l
avum (or vertebral wall) and the dura, just
outside the spinal canal, extending from the foramen magnum to the sacrum. Leads and catheters may
be placed in this space via a needle
Hyperalgesia
Abnormally heightened sensitivity to pain. For pain evoked by stimuli that usually are not painful, the
term allodynia is preferred, while hyperalgesia is more appropriately used for cases with an increased
response at a normal threshold or at an increased threshold
Hypoalgesia
Decreased sensitivity to painful stimuli. Hypoalgesia can be caused by exogenous chemicals such
as opioids, as well as by chemicals produced by the body in phenomena such as fear- and exercise-
induced hypoalgesia
Intrathecal space
The cerebrospinal
/f_l
uid-
/f_i
lled space around the spinal cord, protected by the dura mater, into which
certain medicines may be delivered to achieve their most potent effect
Nociception
Sensory response to certain harmful or potentially harmful stimuli. Nociception triggers a variety of
biological and behavioural responses and may also result in a subjective experience of pain
Neuropathic pain
Neuropathic pain is de
/f_i
ned as pain caused by a lesion or disease of the somatosensory nervous
system
Nociceptive pain
Pain that arises from actual or threatened damage to non-neural tissue and that is due to the activation
of nociceptors
Noxious stimulus
An actual or potential tissue-damaging event
Off-label
When a prescription drug is prescribed for uses other than what Australia’s Therapeutic Goods
Administration, the USA’s Food and Drug Administration or the UK’s Medicines and Healthcare
products Regulatory Agency has approved and published in the drug’s package insert
Pain
An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or
described in terms of such damage
Pain threshold
The minimum amount of a stimulus with which pain begins to be felt. It is an entirely subjective
phenomenon
Paraesthesia
Abnormal cutaneous sensations such as tingling, tickling, pricking or burning with no apparent physical
cause. Often described as ‘pins and needles’ or of a limb ‘falling asleep’
Peripheral neuropathic pain Pain caused by a lesion or disease of the peripheral somatosensory nervous system
of  nerve root irritation associated with or without minor disc prolapse, followed by active physiotherapy and rehabilitation to promote mobility . Nerve stimulation procedures such as acupuncture and transcutaneous nerve stimulation increase endorphin produc tion in the central nervous system. Nerve decompression cra niotomy rather than percutaneous coagulation of the ganglion is now performed for trigeminal neuralgia. Spinal cord stimulation (SCS) by dorsal column stimulation is now a recognised and e ff ective management of  intractable neuropa thic pain ( Figure 23.9 ). This involves placement of electrodes in the posterior epidural space to allow dorsal column stimulation through an implantable pulse generator inserted in the body . In the UK this has been recommended by National Institute for Health and Care Excellence (NICE) guidance for intractable neuropathic pain management. Robust evidence exists for its clinical and health economic benefit in failed back surgery syndrome, in which patients have undergone previous spinal surgery . Early use of  SCS in surgery-naive patients might lead to better outcomes. National guidelines in the UK do not recommend disc replacements or spinal fusions in patients with lower back pain unless the latter are part of  a trial, rendering a large part of  the patient population ineligible for surgery . In these instances, SCS could prove to be an e ff ective solution. Principles of chronic pain management
Non-pharmacological treatment This involves a multidisciplinary approach targeting the biopsychosocial model of  health ( Figure 23.8 ). Early assess - ment and engagement with physiotherapy and exercise are key contributors in successful management. Psychological inter - ventions such as counselling, cognitive behaviour therapy and mindfulness are recognised strategies for pain control. ‘Pain management prog rammes’ lay out a logical structure for this. - Pharmacological treatment Drugs in chronic non-malignant pain Paracetamol and NSAIDs are the mainstays of  musculoskel - etal pain treatment. The tricyclic antidepressant drugs and anticonvulsant agents are often useful for the pain of  nerve injury , although side e ff ects can prove troublesome and reduce compliance. Both pregabalin and gabapentin r educe sponta - neous neuronal activity by their action on the α δ subunit of  the 2 calcium channel. They are now routinely used for managing - neuropathic chronic pain. In more severe and debilitating non-malignant chronic pain, opioid analgesic drugs are used in slow release oral preparations (morphine and oxycodone) and transcutaneous patches (fentanyl and buprenorphine). - - - s - -
Physical
Genetic
health
vulnerabilities
Biological
Disability
Drug
Temperament
effects
IQ
Mental
Peers
Social skills
health
Social
Psychological
Family
relationships
Coping skills
School
Trauma
Family
circumstances
Self-esteem
Figure 23.8
Biopsychosocial model of health.
Commonly used terms in chronic pain Tapentadol, with its dual action on the opioid and noradren aline (norepinephrine) selective reuptake inhibition pathway , may provide relief  in patients with both a neuropathic and nociceptive element to their pain. Combinations of  drugs often prove useful to achie ve the optimum of  e ffi cacy with minimal side e ff ects. Treatment of pain dependent on sympathetic nervous system activity Even minor trauma and surgery (often of  a limb) can provoke excessive sympathetic adrenergic activity , inducing vasocon striction and abnormal nociceptive transmission. This can lead to chronic burning pain, allodynia, trophic changes and resultant disuse. Management includes antineuropathic pain medications - (pregabalin, gabapentin, amitriptyline) as part of  m ultimodal analgesia with a multidisciplinary pain management approach. This includes considerab le input from psychological services and targeted physiotherapy . Interventional treatment may include local anaesthetic injection of  the stellate ganglion for upper limb symptoms. Percutaneous chemical lumbar sympa - thectomy with local anaesthetic is used for relief  of  rest pain in advanced ischaemic disease of  the legs. Interventional pain management for chronic pain - Local anaesthetic and steroid injections can be e ff ective around an inflamed nerve and they reduce the cycle of constant pain transmission with consequent muscle spasm. Transforaminal
Term
De
/f_i
nition
Allodynia
Pain due to a stimulus that does not normally provoke pain. Allodynia involves a change in the quality
of a sensation, whether tactile, thermal or of any other sort
Analgesia
Absence of pain in response to stimulation that would normally be painful
Central sensitisation Increased responsiveness of nociceptive neurones in the central nervous system to their normal or
subthreshold afferent input. The net effect is that innocuous stimuli will be interpreted as painful
Epidural space
The space (or potential space) between the ligamentum
/f_l
avum (or vertebral wall) and the dura, just
outside the spinal canal, extending from the foramen magnum to the sacrum. Leads and catheters may
be placed in this space via a needle
Hyperalgesia
Abnormally heightened sensitivity to pain. For pain evoked by stimuli that usually are not painful, the
term allodynia is preferred, while hyperalgesia is more appropriately used for cases with an increased
response at a normal threshold or at an increased threshold
Hypoalgesia
Decreased sensitivity to painful stimuli. Hypoalgesia can be caused by exogenous chemicals such
as opioids, as well as by chemicals produced by the body in phenomena such as fear- and exercise-
induced hypoalgesia
Intrathecal space
The cerebrospinal
/f_l
uid-
/f_i
lled space around the spinal cord, protected by the dura mater, into which
certain medicines may be delivered to achieve their most potent effect
Nociception
Sensory response to certain harmful or potentially harmful stimuli. Nociception triggers a variety of
biological and behavioural responses and may also result in a subjective experience of pain
Neuropathic pain
Neuropathic pain is de
/f_i
ned as pain caused by a lesion or disease of the somatosensory nervous
system
Nociceptive pain
Pain that arises from actual or threatened damage to non-neural tissue and that is due to the activation
of nociceptors
Noxious stimulus
An actual or potential tissue-damaging event
Off-label
When a prescription drug is prescribed for uses other than what Australia’s Therapeutic Goods
Administration, the USA’s Food and Drug Administration or the UK’s Medicines and Healthcare
products Regulatory Agency has approved and published in the drug’s package insert
Pain
An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or
described in terms of such damage
Pain threshold
The minimum amount of a stimulus with which pain begins to be felt. It is an entirely subjective
phenomenon
Paraesthesia
Abnormal cutaneous sensations such as tingling, tickling, pricking or burning with no apparent physical
cause. Often described as ‘pins and needles’ or of a limb ‘falling asleep’
Peripheral neuropathic pain Pain caused by a lesion or disease of the peripheral somatosensory nervous system
of  nerve root irritation associated with or without minor disc prolapse, followed by active physiotherapy and rehabilitation to promote mobility . Nerve stimulation procedures such as acupuncture and transcutaneous nerve stimulation increase endorphin produc tion in the central nervous system. Nerve decompression cra niotomy rather than percutaneous coagulation of the ganglion is now performed for trigeminal neuralgia. Spinal cord stimulation (SCS) by dorsal column stimulation is now a recognised and e ff ective management of  intractable neuropa thic pain ( Figure 23.9 ). This involves placement of electrodes in the posterior epidural space to allow dorsal column stimulation through an implantable pulse generator inserted in the body . In the UK this has been recommended by National Institute for Health and Care Excellence (NICE) guidance for intractable neuropathic pain management. Robust evidence exists for its clinical and health economic benefit in failed back surgery syndrome, in which patients have undergone previous spinal surgery . Early use of  SCS in surgery-naive patients might lead to better outcomes. National guidelines in the UK do not recommend disc replacements or spinal fusions in patients with lower back pain unless the latter are part of  a trial, rendering a large part of  the patient population ineligible for surgery . In these instances, SCS could prove to be an e ff ective solution.

Regional anaesthesia
Regional anaesthesia
Regional anaesthesia involves central neuraxial or peripheral nerve or plexus blocks using local anaesthetic drugs. It has a clear advantage when general anaesthesia carries a higher risk of  morbidity and mortality , such as in patients with debilitating respiratory and cardiovascular disease and obstetric cases. It also provides excellent pain relief  in the postoperative period, reducing the need for analgesics such as opioids. As with general anaesthesia, venous access should be established and vital parameters should be monitored during regional anaesthesia. Localising nerves using anatomical landmarks and eliciting paraesthesia alone carries a high risk of  nerve damage and intravascular injection and has a lower success rate. The use of nerve stimulators to localise nerves impro ves the success rate and reduces risks. Ultrasound-guided regional anaesthesia allows the visualisation of  nerves and the spread of  local anaes thetics, enabling the use of  a smaller dose of  local anaesthetic agents with improved success rates and safety . Summary box 23.8 Types of anaesthesia /uni25CF /uni25CF /uni25CF /uni25CF
General anaesthesia may be more acceptable to patients
Regional anaesthesia has major advantages in obstetrics and
patients with respiratory compromise
Local blocks have been transformed by nerve stimulators and
ultrasound guidance
All require full resuscitation and monitoring equipment to be
available
Regional anaesthesia
Regional anaesthesia involves central neuraxial or peripheral nerve or plexus blocks using local anaesthetic drugs. It has a clear advantage when general anaesthesia carries a higher risk of  morbidity and mortality , such as in patients with debilitating respiratory and cardiovascular disease and obstetric cases. It also provides excellent pain relief  in the postoperative period, reducing the need for analgesics such as opioids. As with general anaesthesia, venous access should be established and vital parameters should be monitored during regional anaesthesia. Localising nerves using anatomical landmarks and eliciting paraesthesia alone carries a high risk of  nerve damage and intravascular injection and has a lower success rate. The use of nerve stimulators to localise nerves impro ves the success rate and reduces risks. Ultrasound-guided regional anaesthesia allows the visualisation of  nerves and the spread of  local anaes thetics, enabling the use of  a smaller dose of  local anaesthetic agents with improved success rates and safety . Summary box 23.8 Types of anaesthesia /uni25CF /uni25CF /uni25CF /uni25CF
General anaesthesia may be more acceptable to patients
Regional anaesthesia has major advantages in obstetrics and
patients with respiratory compromise
Local blocks have been transformed by nerve stimulators and
ultrasound guidance
All require full resuscitation and monitoring equipment to be
available
Regional anaesthesia
Regional anaesthesia involves central neuraxial or peripheral nerve or plexus blocks using local anaesthetic drugs. It has a clear advantage when general anaesthesia carries a higher risk of  morbidity and mortality , such as in patients with debilitating respiratory and cardiovascular disease and obstetric cases. It also provides excellent pain relief  in the postoperative period, reducing the need for analgesics such as opioids. As with general anaesthesia, venous access should be established and vital parameters should be monitored during regional anaesthesia. Localising nerves using anatomical landmarks and eliciting paraesthesia alone carries a high risk of  nerve damage and intravascular injection and has a lower success rate. The use of nerve stimulators to localise nerves impro ves the success rate and reduces risks. Ultrasound-guided regional anaesthesia allows the visualisation of  nerves and the spread of  local anaes thetics, enabling the use of  a smaller dose of  local anaesthetic agents with improved success rates and safety . Summary box 23.8 Types of anaesthesia /uni25CF /uni25CF /uni25CF /uni25CF
General anaesthesia may be more acceptable to patients
Regional anaesthesia has major advantages in obstetrics and
patients with respiratory compromise
Local blocks have been transformed by nerve stimulators and
ultrasound guidance
All require full resuscitation and monitoring equipment to be
available

Ventilation during anaesthesia
Ventilation during anaesthesia
Mechanical ventilation is required when the patient’s spon taneous ventilation is inadequate or when the patient is not breathing because of  the e ff ects of  the anaesthetic, analgesic agents or muscle relaxants. In volume control ventilation, a preset volume is deliver by the machine irrespective of  the airway pressure. The pres sure generated will be, in part, dependent on the r esistance and compliance of the airway . In laparoscopic surgery requir ing the Trendelenbur g position (the patient is positioned head down), morbidly obese patients and those with lung disease, this may result in excessive pressures being developed, which ma y lead to barotrauma (pneumothorax). In pressure control mode the ventilator generates flow until a preset pressure is reached. The actual tidal volume delivered is variable and depends on airway resistance, intra-abdominal pressure and the deg ree of  relaxation. Positive end-expiratory pressure (PEEP) is often applied to help maintain functional residual capacity . This avoids lung collapse by opening collapsed alveoli and maintains a greater area of  gas exchange, so r educing vascular shunting. Ventilation during anaesthesia
Mechanical ventilation is required when the patient’s spon taneous ventilation is inadequate or when the patient is not breathing because of  the e ff ects of  the anaesthetic, analgesic agents or muscle relaxants. In volume control ventilation, a preset volume is deliver by the machine irrespective of  the airway pressure. The pres sure generated will be, in part, dependent on the r esistance and compliance of the airway . In laparoscopic surgery requir ing the Trendelenbur g position (the patient is positioned head down), morbidly obese patients and those with lung disease, this may result in excessive pressures being developed, which ma y lead to barotrauma (pneumothorax). In pressure control mode the ventilator generates flow until a preset pressure is reached. The actual tidal volume delivered is variable and depends on airway resistance, intra-abdominal pressure and the deg ree of  relaxation. Positive end-expiratory pressure (PEEP) is often applied to help maintain functional residual capacity . This avoids lung collapse by opening collapsed alveoli and maintains a greater area of  gas exchange, so r educing vascular shunting. Ventilation during anaesthesia
Mechanical ventilation is required when the patient’s spon taneous ventilation is inadequate or when the patient is not breathing because of  the e ff ects of  the anaesthetic, analgesic agents or muscle relaxants. In volume control ventilation, a preset volume is deliver by the machine irrespective of  the airway pressure. The pres sure generated will be, in part, dependent on the r esistance and compliance of the airway . In laparoscopic surgery requir ing the Trendelenbur g position (the patient is positioned head down), morbidly obese patients and those with lung disease, this may result in excessive pressures being developed, which ma y lead to barotrauma (pneumothorax). In pressure control mode the ventilator generates flow until a preset pressure is reached. The actual tidal volume delivered is variable and depends on airway resistance, intra-abdominal pressure and the deg ree of  relaxation. Positive end-expiratory pressure (PEEP) is often applied to help maintain functional residual capacity . This avoids lung collapse by opening collapsed alveoli and maintains a greater area of  gas exchange, so r educing vascular shunting.