Dyspnea

Dyspnea is an uncomfortable awareness of breathing. It is a common symptom of cardiac and pulmonary diseases, and may also result from neurological conditions, chest wall problems, and anxiety states.

Differential Diagnosis of dyspnea (see Table 2-1)

Cardiac causes of dyspnea predominantly relate to increased pressure in the left ventricle and/or atrium.

This pressure is transmitted back to the lungs where it results in transudation of fluid into the interstitial and alveolar spaces, and interferes with alveolar gas exchange. This can occur as a result of:

• valvular heart disease (mitral or aortic regurgitation or stenosis)
• left ventricular systolic dysfunction (ischemic or non-ischemic cardiomyopathies)
• left ventricular diastolic dysfunction (e.g., left ventricular hypertrophy, acute myocardial ischemia, infiltrative cardiomyopathy)
• pericardial diseases (pericardial constriction or tamponade)

Pulmonary causes of dyspnea may result from abnormalities of the tracheobronchial tree, alveolae, pulmonary vasculature, or pleura. These include:

• pneumoma
• chronic obstructive pulmonary disease (COPD)
• asthma
• pulmonary embolism (PE)
• pneumothorax
• pulmonary fibrosis
• pulmonary hypertension
• pleural effusion
• airway obstruction
• diaphragmatic paralysis

Dyspnea may also be a feature of anemia, hyperthyroidism, obesity, neurological disorders that effect the respiratory muscles, physical deconditioning, and anxiety.

Clinical Manifestations

History

Several historical features may help differentiate between causes of dyspnea. The sudden onset of dyspnea may occur with angina, pulmonary edema, pneumothorax, or PE. Slowly progressive dyspnea may result from COPD, pleural effusions, anemia, or chronic congestive heart failure (CHF). Other historical features that implicate specific causes of dyspnea include:

• chest pain (angina, myocardial infarction (MI), pneumonia, PE, pneumothorax)
• cough (pneumonia, bronchitis, asthma)
• fever (pneumonia, bronchitis)
• hemoptysis (PE, bronchitis)
• history of smoking (COPD)
• cardiac risk factors (angina, MI)
• chest wall trauma (pneumothorax)

It is also important to note the pattern of dyspnea.

Dyspnea is frequently precipitated by exertion irrespective of its cause. Dyspnea that occurs at rest usually indicates severe cardiac or pulmonary disease. Paroxysmal nocturnal dyspnea suggests left heart failure; this usually occurs 2 to 4 hours into sleep and requires that the patient sit up or get out of bed to obtain relief. Orthopnea is often a symptom of heart failure, but can also occur as a result of pulmonary disorders.