Use and limitations of clinical and radiologic diagnosis of pneumonia

Pneumonia remains foremost a clinical diagnosis. However, symptoms of lower respiratory infection, including fever, cough, purulent sputum, dyspnea, and pleuritic pain as well as the clinical findings of tachypnea, tachycardia, hypoxemia, and auscultatory signs of consolidation, are not unique to pneumonia. Chest radiographs are therefore routinely required to confirm the clinical suspicion of pneumonia. This article discusses the limitations and pitfalls in the clinical and radiographic diagnosis of both community-acquired pneumonia and hospital-acquired, especially ventilator-associated, pneumonia. Given the difficulties of clinical diagnosis in pneumonia, empiric antibiotic treatment often is used. Inherent in the use of empiric therapy is the assumption that a favorable clinical response indicates both that pneumonia is present and that the empiric treatment is adequate. An accurate assessment of the normal, expected response of pneumonia to antibiotic therapy is therefore crucial. A discussion of the clinical response to treatment concludes the article.