# 01 - SECTION 1 Diagnosis of Respiratory Disorders

## SECTION 1 Diagnosis of Respiratory Disorders

Section 1	 Diagnosis of Respiratory 
Disorders
Bruce D. Levy

Approach to the Patient 

with Disease of the 

Respiratory System
The majority of diseases of the respiratory system present with cough 
and/or dyspnea and fall into one of three major categories: (1) obstruc­
tive; (2) restrictive; and (3) vascular diseases. Obstructive pathophysi­
ology is most common and primarily results from airway diseases, such 
as asthma, chronic obstructive pulmonary disease (COPD), bronchiec­
tasis, and bronchiolitis. Diseases resulting in restrictive pathophysiol­
ogy include parenchymal lung diseases, abnormalities of the chest wall 
and pleura, and neuromuscular disease. Pulmonary embolism, pulmo­
nary hypertension, and pulmonary venoocclusive disease are examples 
of disorders of the pulmonary vasculature. Although many specific 
diseases fall into these major categories, both infective and neoplas­
tic processes can affect the respiratory system and result in myriad 
pathologic findings, including those listed in the three categories above 
(Table 295-1).
Disorders can also be grouped according to gas exchange abnor­
malities, including hypoxemia, hypercarbia, or combined impairment; 
however, many respiratory disorders do not manifest as gas exchange 
abnormalities.
As with the evaluation of most patients, the approach to a patient 
with a respiratory system disorder begins with a thorough history 
TABLE 295-1  Categories of Respiratory Disease
CATEGORY
EXAMPLES
Obstructive pathophysiology—
airway disease
Asthma
Chronic obstructive pulmonary disease 
(COPD)
Bronchiectasis
Bronchiolitis
Restrictive pathophysiology—
parenchymal disease
Idiopathic pulmonary fibrosis (IPF)
Asbestosis
Desquamative interstitial pneumonitis (DIP)
Sarcoidosis
Restrictive pathophysiology—
neuromuscular weakness
Amyotrophic lateral sclerosis (ALS)
Guillain-Barré syndrome
Myasthenia gravis
Restrictive pathophysiology—
chest wall/pleural disease
Kyphoscoliosis
Ankylosing spondylitis
Chronic pleural effusions
Pulmonary vascular disease
Pulmonary embolism
Pulmonary arterial hypertension (PAH)
Pulmonary venoocclusive disease
Vasculitis
Malignancy
Bronchogenic carcinoma (non-small-cell 
and small-cell lung cancer)
Metastatic disease
Infectious diseases
Pneumonia
Bronchitis
Tracheitis

Disorders of the Respiratory System
PART 7
and a focused physical examination. Many patients will subsequently 
undergo pulmonary function testing, chest imaging, blood and sputum 
analysis, a variety of serologic or microbiologic studies, and diagnostic 
procedures, such as bronchoscopy. This stepwise approach is discussed 
in detail below.
■
■HISTORY
Dyspnea and Cough 
The cardinal symptoms of respiratory dis­
ease are dyspnea and cough (Chaps. 39 and 40). Dyspnea has many 
causes, some of which are not predominantly due to lung pathology. 
The words a patient uses to describe shortness of breath can suggest 
certain etiologies for dyspnea. Patients with obstructive lung disease 
often complain of “chest tightness” or “inability to get a deep breath,” 
whereas patients with congestive heart failure more commonly report 
“air hunger” or a sense of suffocation.
The tempo of onset and the duration of a patient’s dyspnea are 
likewise helpful in determining the etiology. Acute shortness of breath 
is usually associated with sudden physiologic changes, such as acute 
airway narrowing (e.g., laryngeal edema, bronchospasm, or mucus 
plugging), acute hypoxemia (e.g., pulmonary edema, pneumonia, or 
pulmonary embolism), or sudden changes in the work of breathing 
(e.g., pneumothorax). Patients with COPD and idiopathic pulmonary 
fibrosis (IPF) experience a gradual progression of dyspnea on exertion, 
punctuated by acute exacerbations of shortness of breath. In contrast, 
most asthmatics do not have daily symptoms, but experience intermit­
tent episodes of dyspnea, cough, and chest tightness that are usually 
associated with specific triggers, such as an upper respiratory tract 
infection or exposure to allergens.
Specific questioning should focus on factors that incite dyspnea as 
well as on any intervention that helps resolve the patient’s shortness of 
breath. Asthma is commonly exacerbated by specific triggers, although 
this can also be true of COPD. Many patients with lung disease report 
dyspnea on exertion. Determining the degree of activity that results in 
shortness of breath gives the clinician a gauge of the patient’s degree of 
disability. Many patients adapt their level of activity to accommodate 
progressive limitation. For this reason, it is important, particularly in 
older patients, to delineate the activities in which they engage and how 
these activities have changed over time. Dyspnea on exertion is often 
an early symptom of underlying lung or heart disease and warrants a 
thorough evaluation.
For cough, the clinician should inquire about the duration of the 
cough, whether or not it is associated with sputum production, and 
any specific triggers that induce it. Acute cough productive of phlegm 
is often a symptom of infection of the respiratory system, including 
processes affecting the upper airway (e.g., sinusitis, tracheitis), the 
lower airways (e.g., bronchitis, bronchiectasis), and the lung paren­
chyma (e.g., pneumonia). Both the quantity and quality of the sputum, 
including whether it is blood-streaked or frankly bloody, should be 
determined. Hemoptysis warrants urgent evaluation as delineated in 
Chap. 41.
Chronic cough (defined as that persisting for >8 weeks) is com­
monly associated with obstructive lung diseases, particularly asthma, 
COPD, and chronic bronchiectasis, as well as “nonrespiratory” dis­
eases, such as gastroesophageal reflux and postnasal drip. Diffuse 
parenchymal lung diseases, including IPF, frequently present as a per­
sistent, nonproductive cough. All causes of cough are not respiratory in 
origin, and assessment should encompass a broad differential, includ­
ing cardiac and gastrointestinal diseases as well as psychogenic causes.
Additional Symptoms 
Patients with respiratory disease may 
report wheezing, which is suggestive of airways disease, particularly 
asthma. Hemoptysis can be a symptom of a variety of lung diseases, 
including infections of the respiratory tract, bronchogenic carcinoma, 
and pulmonary embolism. In addition, chest pain or discomfort can be 
respiratory in origin. As the lung parenchyma is not innervated with 
pain fibers, pain in the chest from respiratory disorders usually results