Degree of haemorrhage and classification

Degree of haemorrhage and classification

The adult human has approximately 5 litres of blood (70 /uni00A0 mL/kg for children and adults, 80 /uni00A0 mL/kg for neonates). Estimation of the amount of blood that has been lost is di ffi cult, inaccurate and usually underestimates the actual value. External haemorrhage is obvious, but it may be di ffi cult to estimate the actual volume lost. In the operating theatre, blood collected in suction apparatus can be measur ed and swabs soaked in blood weighed. - The haemoglobin level is a poor indicator of the degree of haemorrhage because it represents a concentration and not an absolute amount. In the early stages of rapid haemorrhage, the haemoglobin concentra tion is unchanged (as whole blood is lost). Later, as fluid shifts from the intracellular and interstitial - spaces into the vascular compartment, the haemoglobin and haematocrit levels will fall.

Class 2 3 4 15–30% 30–40%

40%

classes 1–4 based on the estimated blood loss required to pro duce certain physiological compensatory changes ( Table 2.3 Although conceptually useful, this classification system is never applied clinically , and indeed is di ffi cult if not impossible to determine. There is variation in clinical response across ages (the young compensate well, the old very poorly), variation among individuals (e.g. athletes versus the obese) and variation owing to confounding factors (e.g. concomitant medications, pain). Degree of haemorrhage and classification

The adult human has approximately 5 litres of blood (70 /uni00A0 mL/kg for children and adults, 80 /uni00A0 mL/kg for neonates). Estimation of the amount of blood that has been lost is di ffi cult, inaccurate and usually underestimates the actual value. External haemorrhage is obvious, but it may be di ffi cult to estimate the actual volume lost. In the operating theatre, blood collected in suction apparatus can be measur ed and swabs soaked in blood weighed. - The haemoglobin level is a poor indicator of the degree of haemorrhage because it represents a concentration and not an absolute amount. In the early stages of rapid haemorrhage, the haemoglobin concentra tion is unchanged (as whole blood is lost). Later, as fluid shifts from the intracellular and interstitial - spaces into the vascular compartment, the haemoglobin and haematocrit levels will fall.

Class 2 3 4 15–30% 30–40%

40%

classes 1–4 based on the estimated blood loss required to pro duce certain physiological compensatory changes ( Table 2.3 Although conceptually useful, this classification system is never applied clinically , and indeed is di ffi cult if not impossible to determine. There is variation in clinical response across ages (the young compensate well, the old very poorly), variation among individuals (e.g. athletes versus the obese) and variation owing to confounding factors (e.g. concomitant medications, pain). Degree of haemorrhage and classification

The adult human has approximately 5 litres of blood (70 /uni00A0 mL/kg for children and adults, 80 /uni00A0 mL/kg for neonates). Estimation of the amount of blood that has been lost is di ffi cult, inaccurate and usually underestimates the actual value. External haemorrhage is obvious, but it may be di ffi cult to estimate the actual volume lost. In the operating theatre, blood collected in suction apparatus can be measur ed and swabs soaked in blood weighed. - The haemoglobin level is a poor indicator of the degree of haemorrhage because it represents a concentration and not an absolute amount. In the early stages of rapid haemorrhage, the haemoglobin concentra tion is unchanged (as whole blood is lost). Later, as fluid shifts from the intracellular and interstitial - spaces into the vascular compartment, the haemoglobin and haematocrit levels will fall.

Class 2 3 4 15–30% 30–40%

40%

classes 1–4 based on the estimated blood loss required to pro duce certain physiological compensatory changes ( Table 2.3 Although conceptually useful, this classification system is never applied clinically , and indeed is di ffi cult if not impossible to determine. There is variation in clinical response across ages (the young compensate well, the old very poorly), variation among individuals (e.g. athletes versus the obese) and variation owing to confounding factors (e.g. concomitant medications, pain).