Utility of bilateral bronchoalveolar lavage for the diagnosis of ventilator-associated pneumonia in critically ill surgical patients

Background Bronchoalveolar lavage (BAL) is recommended to facilitate the diagnosis of ventilator-associated pneumonia (VAP). It is unclear if bilateral sampling improves the accuracy of BAL. Methods Consecutive patients with clinical suspicion for VAP were analyzed. All patients underwent bilateral BAL. A threshold of >104 colony-forming units (cfu)/mL was diagnostic for VAP (VAP positive). Samples were concordant if the organism(s) and thresholds from both lungs were diagnostically consistent. Organisms ≤104 cfu/mL with growth on the contralateral sample >104 cfu/mL were considered false-negative samples. Results Between November 2005 and April 2006, 73 patients were considered clinically suspicious for VAP. Forty-four (60%) patients were VAP positive. Twenty-eight (64%) VAP patients had concordant samples. Overall, there were 15 false-negative samples. Sole use of the unilateral samples to guide treatment would have inappropriately directed antibiotic avoidance and/or discontinuation in 25% of VAP patients. Influence of the chest radiograph was equivocal because of the presence of bilateral infiltrates in 80% of discordant samples. Conclusions Bilateral BAL improves the accuracy of bronchoscopy in diagnosing VAP. Unilateral BAL may be insensitive in patients with clinically significant contralateral infection.