Does BAL Affect Outcome In Ventilator-Associated Pneumonia?
ABSTRACT & COMMENTARY
In this study from the University of Buenos Aires, Argentina, 132 mechanically ventilated adult patients who were clinically suspected of having ventilator-associated pneumonia (VAP) were studied prospectively. Standard criteria were used for making the clinical diagnosis of VAP: at least two of three clinical findings (fever or hypothermia, leukocytosis or leukopenia, and/or purulent bronchial secretions), plus a new or progressive infiltrate on chest X-ray. All patients underwent bronchoscopy with bronchoalveolar lavage (BAL) and were given empirical antimicrobial therapy that started either before (n = 107) or immediately after (n = 25) BAL.
Of the 132 patients with a clinical diagnosis of VAP, BAL findings were positive (> 10,000 bacterial colony-forming units per mL) in 65 and negative in 67. The BAL-positive patients were more likely to have all of the clinical entry criteria, but there were no differences in mortality, prior antibiotic use, or demographic features when compared with the BAL-negative patients. Among BAL-positive patients who were already on antibiotics when BAL was performed, mortality was 38% if the initial antibiotics proved to be appropriate according to culture results; if BAL cultures showed organisms not covered by the empirical antibiotics, the mortality rate was 91% (P < 0.001). When antibiotic changes were made after the BAL results became available, more patients received appropriate therapy, but the mortality rate was the same as in those who continued to receive inappropriate antibiotics. (Luna CM, et al. Chest 1997;111:676-685.)
COMMENT BY DAVID J. PIERSON, MD
This study confirms the findings of previous investigators that patients who meet clinical criteria for VAP have a high mortality rate. Whether these patients also met the requirement for a positive BAL culture (increasingly used as a diagnostic criterion for VAP) made no difference in outcome once they had the clinical features of the illness. This finding is important, particularly if other studies can confirm it, in view of the controversy raging over whether invasive (and expensive) diagnostic procedures are necessary to diagnose VAP (see opposing viewpoints of Chastre J, et al. Am J Respir Crit Care Med 1994;150:570-574; and Niederman MS, et al. Am J Respir Crit Care Med 1994;150:565-569).
Also of great interest to clinicians is the finding in this study that initial empiric antibiotic therapy seems to make the difference in outcome in VAP. If this therapy proved to have been appropriate, the patients did much better than if it did not, regardless of whether the antibiotic coverage was modified on the basis of the BAL results. Luna et al found that if adequate antimicrobial therapy was delayed until bronchoscopy was performed, or until BAL results were known, mortality was higher than if it had been given when the clinical diagnosis of VAP was first entertained. These results imply that bronchoscopy and BAL do not affect the outcome of critically ill patients who develop VAP, even if they can more precisely define its etiology. While it will be important to confirm these findings in other centers, based on this study bronchoscopy and BAL would not appear to be mandated in order to properly manage a patient who develops the clinical features of VAP. These findings also underscore the importance of wise initial antibiotic use, selecting not automatically the broadest possible coverage but rather a regimen aimed at covering the organisms most likely in the individual patient, given his or her underlying condition, previous culture results, and the prevalence of various pathogens in the specific unit at the time.
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