Differences in management and mortality with a bronchoalveolar lavage-based diagnostic protocol for ventilator-associated pneumonia

Abstract

Directed antibiotic therapy based on accurate bacteriology is critical to ventilator-associated pneumonia (VAP) treatment. Bronchoalveolar lavage (BAL) has been reported to be more accurate than endotracheal sputum aspirate (ESA) in VAP diagnosis. Our objective was to determine the frequency with which BAL results differ from ESA cultures and the outcomes of VAP with a BAL-based VAP protocol. Prospectively collected microbiologic data on all trauma patients with VAP from 2007 through 2009 were reviewed. Per protocol, a positive ESA prompts a BAL and initiation of broad empiric antibiotics with de-escalation based on BAL results. Patients diagnosed with VAP by the protocol were compared with those diagnosed outside of the protocol using univariate and multivariate linear regression analysis. Concordance of ESA and BAL results was evaluated, and cause of death was determined. Of 137 patients with VAP, 96 were diagnosed by the protocol (protocol group) and had 102 pairs of cultures. Twenty-six patients (27%) with 28 pairs of cultures (27.4%) had discordant results. Of discordant pairs, 17 (61%) showed bacteria of a different Gram's stain. Methicillin-sensitive Staphylococcus aureus was the most common causative organism. Mortality was lower in the protocol group (6.3%) than the nonprotocol group (22%, p = 0.014) and mechanically ventilated patients without VAP (24%, p = 0.35) but with comparable Injury Severity Score (ISS). VAP-attributable mortality in the protocol group was 1%. Use of a BAL-based diagnostic protocol affects management of trauma patients with VAP by improving identification of causative microorganisms and is associated with low overall mortality and VAP-attributable mortality.