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A 67-year-old man comes to your clinic for his annual appointment concerned about increasing shortness of breath. A year ago he was able to walk up the stairs to his apartment without difficulty, but now he has difficulty walking one block. He has a 70 pack-year smoking history, and several previous attempts to stop smoking have been unsuccessful.


  • Does the patient require urgent intervention?
  • Is the shortness of breath acute or chronic?
  • What additional questions would you ask to learn more about his shortness of breath?
  • What is the organ system involved in the patient's shortness of breath (cardiac, pulmonary, hematologic, or psychiatric)?


Shortness of breath, or dyspnea, is the sensation of uncomfortable breathing. This feeling of discomfort may reflect an increased awareness of breathing or the perception that breathing is difficult or inadequate. Dyspnea usually indicates pulmonary or cardiac disease, but can also be the presenting symptom of metabolic derangements, hematologic disorders, toxic ingestions, psychiatric conditions, or simple deconditioning. Dyspnea is the second most common reason for emergency department visits in the United States.1


Dyspnea can be classified based on the primary physiologic derangement:

  • Pulmonary
  • Cardiac
  • Hematologic (eg, anemia)
  • Chest wall or neuromuscular disease
  • Metabolic (eg, acidosis)
  • Functional (eg, panic disorders)
  • Deconditioning

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CardiomyopathiesConditions that damage heart muscle and may cause heart failure. Etiologies are diverse. Common causes include ischemic heart disease, valvular disease, hypertension, infections, toxins, and genetic disorders.
DyspneaAbnormally increased awareness of breathing or sensation of difficulty breathing.
Interstitial lung diseaseA heterogeneous set of conditions characterized by hypoxia and interstitial (pulmonary vessels, bronchi, connective tissue) abnormalities on chest radiographs. Examples include sarcoidosis, idiopathic pulmonary fibrosis, rheumatoid lung, and pneumoconioses.
OrthopneaDyspnea when lying flat. Typically described in terms of the number of pillows the patient uses to breathe comfortably to sleep.
Paroxysmal nocturnal dyspnea (PND)Dyspnea that wakes the patient from sleep. The patient may report waking up gasping for air, and classically finds relief by sitting by an open window.
PlatypneaDyspnea that improves when the patient lies down.
TrepopneaDyspnea that occurs in the lateral decubitus position on one side, but not the other.

The purpose of breathing is to meet the metabolic demands of the body. Thus, any condition that increases the work of breathing (eg, airway obstruction, changes in lung compliance, or respiratory muscle weakness) or increases respiratory drive (eg, hypoxia or acidosis) may result in dyspnea.2 In addition, dyspnea may result from or be exacerbated by primary psychological conditions (eg, anxiety disorders).


The differential diagnosis of dyspnea depends on the duration of the symptom and the clinical setting. Conditions associated with acute dyspnea (developing over hours to a few days) are outlined under alarm conditions.


Conditions associated with insidious development of dyspnea are outlined below. In an analysis of patients referred to a pulmonary clinic ...

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