RATIONALE: Open lung biopsy may be performed to guide therapy in mechanically ventilated patients with diagnostic uncertainty regarding etiology of pulmonary infiltrates. Current evidence for open lung biopsy in mechanically ventilated patients comes from single center case series.

METHODS: We searched Medline for case series of lung biopsies in critically ill patients requiring mechanical ventilation. We pooled results of individual case series using random effects meta-analysis models to obtain summary proportions.

MEASUREMENTS AND RESULTS: We identified 14 case series including a total of 512 mechanically ventilated patients with 530 histopathological diagnoses. The most common diagnoses were 'fibrosis/pneumonitis' (n = 155, 25%; 95% CI 14-37%) and infection (n = 113, 20%; 95% CI 15%-27%). Viruses were the most commonly identified infectious etiology identified on open lung biopsy, representing 50% of potential pathogens. Diffuse alveolar damage was present in a minority of specimens (n = 100, 16%; 95% CI 8%-25%). Therapeutic changes following lung biopsy occurred in 399 patients (78%; 95% CI 64%-81%). Procedure-related complications occurred in 29% of patients (95% CI 25%-33%), most commonly persistent air leak. Mortality among mechanically ventilated patients following diagnostic open lung biopsy was 54%.

CONCLUSIONS: Among mechanically ventilated patients with respiratory failure of unclear etiology, lung biopsy yielded a wide range of diagnoses and was associated with a change in therapy in most patients.

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