RESUMEN
Distinguishing pneumonia from other causes of respiratory illnesses, such as bronchitis, influenza and upper respiratory tract infections, has important therapeutic and prognostic implications. This decision is usually made by clinical assessment alone or by performing a chest x-ray. The reference standard for diagnosing pneumonia is chest radiography, but many physicians rely on history and physical examination to diagnose or exclude this disease. A review of published studies of patients suspected of having pneumonia reveals that there are no individual clinical findings, or combination of findings, that can predict with certainty the diagnosis of pneumonia. Prediction rules have been recommended to guide the order of diagnostic tests, to maximize their clinical utility. Thus, some studies have shown that the absence of any vital sign abnormalities or any abnormalities on chest auscultation substantially reduces the likelihood of pneumonia to a point where further diagnostic evaluation may be unnecessary. This article reviews the literature on the appropriate use of the history and physical examination in diagnose community-acquired pneumonia.