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- Pneumonia is one of the leading causes of respiratory failure leading to admission to the intensive care unit and is by far the most common nosocomial infection in critically ill patients.
- Mortality rate may exceed 50% for severe community-acquired pneumonia (CAP) requiring admission to the intensive care unit and varies from 30% to 60% in nosocomial cases.
- The initial approach to diagnostic testing and empiric therapy is guided by the clinical presentation of the pneumonia, which can be categorized as follows: CAP, acute CAP, aspiration pneumonia/lung abscess, and chronic pneumonia; nosocomial pneumonia; and pulmonary infiltrate in immunocompromised host.
- Investigation of acute pneumonia should always include a blood culture and Gram stain and culture of lower respiratory tract secretions. Smear and culture for Legionella species and serologic testing for other atypical pathogens should be done when atypical pneumonia features are present and in otherwise undiagnosed cases of severe pneumonia.
- Fiberoptic bronchoscopy with quantitative bacteriology of a protected brush specimen or bronchoalveolar lavage specimen is the procedure of choice for diagnosis of acute CAP and nosocomial pneumonia that respond poorly to treatment and resist diagnosis by noninvasive means.
- Empiric intravenous antimicrobial therapy should be begun immediately in all critically ill patients with an acute pneumonia. Antimicrobial coverage should include all pathogens of more than trivial probability and should always include Streptococcus pneumoniae, Staphylococcus aureus, and Enterobacteriaceae. In cases of severe pneumonia of unknown cause, a fluoroquinolone should be included to cover Legionella species, and dual antimicrobial coverage for Pseudomonas species should be given to patients at special risk of carrying this organism.
- Empiric antimicrobial therapy initially can be withheld in less severely ill patients in whom the diagnosis of infectious pneumonia is in doubt and in patients with a chronic pneumonia presentation, pending definitive diagnosis.
- Pulmonary infiltrates in an immunocompromised host may be caused by any of the infectious agents affecting the normal population, by opportunistic infections, or by noninfectious processes. The required approach combines empiric therapy, selected on the basis of the particular infectious agents for which the patient is at special risk, with a timely stepwise diagnostic approach that moves from noninvasive testing to fiberoptic bronchoscopy to open lung biopsy at a rate determined by the rate of progression of the patient's undiagnosed pneumonia.
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Pneumonia remains the leading infectious cause of death in the developed world. It is also the most frequent infection leading to admission to most intensive care units (ICUs) and by far the most important nosocomial infection complicating the treatment of patients admitted to ICUs for other problems. Roughly 5% to 10% of patients hospitalized for community-acquired pneumonia (CAP) require ICU admission, with a mortality rate of 30% to 50%.1–3 Pneumonia is also the most important nosocomial infection leading to ICU admission and a frequent complication of treatment in an ICU, occurring in 5% to 50% of patients requiring mechanical ventilation.4 A systematic approach and an aggressive attitude toward diagnosis and treatment of pneumonia therefore are fundamental to good ...