The development of shortness of breath (SOB) is an expected outcome of overexertion,
as normally occurs after strenuous exercise. SOB occurring at rest or during marginal
exertion is considered abnormal. Multiple organ systems are involved in the differential
diagnosis of SOB but for the purpose of this article, we concentrate on the pulmonary
system and include chronic obstructive pulmonary disease (COPD), asthma, pneumonia,
pneumothorax, interstitial lung disease, lung cancer and dysfunctional breathlessness. This is
the second in a series of three articles focusing on diagnosis of the breathless patient.
