Approach to the Patient with Disease of the Respiratory System
The majority of diseases of the respiratory system fall into one of three major categories: (1) obstructive lung diseases; (2) restrictive disorders; and (3) abnormalities of the vasculature. Obstructive lung diseases are most common and primarily include disorders of the airways, such as asthma, chronic obstructive pulmonary disease (COPD), bronchiectasis, and bronchiolitis. Diseases resulting in restrictive pathophysiology include parenchymal lung diseases, abnormalities of the chest wall and pleura, and neuromuscular disease. Disorders of the pulmonary vasculature include pulmonary embolism, pulmonary hypertension, and pulmonary veno-occlusive disease. Although many specific diseases fall into these major categories, both infective and neoplastic processes can affect the respiratory system and result in myriad pathologic findings, including those listed in the three categories above (Table 305–1).
TABLE 305-1Categories of Respiratory Disease |Favorite Table|Download (.pdf) TABLE 305-1 Categories of Respiratory Disease
|Category ||Examples |
|Obstructive lung disease || |
Chronic obstructive pulmonary disease (COPD)
|Restrictive pathophysiology—parenchymal disease || |
Idiopathic pulmonary fibrosis (IPF)
Desquamative interstitial pneumonitis (DIP)
|Restrictive pathophysiology—neuromuscular weakness || |
Amyotrophic lateral sclerosis (ALS)
|Restrictive pathophysiology—chest wall/pleural disease || |
Chronic pleural effusions
|Pulmonary vascular disease || |
Pulmonary arterial hypertension (PAH)
|Malignancy || |
Bronchogenic carcinoma (non-small-cell and small-cell)
|Infectious diseases || |
Disorders can also be grouped according to gas exchange abnormalities, including hypoxemic, hypercarbic, or combined impairment. However, many diseases of the lung do not manifest as gas exchange abnormalities.
As with the evaluation of most patients, the approach to a patient with disease of the respiratory system begins with a thorough history 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.
The cardinal symptoms of respiratory disease are dyspnea and cough (Chaps. 47e and 48). 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 laryngeal edema, bronchospasm, myocardial infarction, pulmonary embolism, or 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, ...