ROLE OF BRONCHOALVEOLAR LAVAGE IN MECHANICALLY VENTILATED PATIENTS WITH SUSPECTED PNEUMONIA

To determine the usefulness of samples obtained by bronchoalveolar lav age (BAL) in establishing the diagnosis of ventilator-associated pneum onia, quantitative cultures of BAL and protected specimen brush (PSB) samples obtained via fiberoptic bronchoscope were compared in 42 patie nts with suspected ventilator-associated pneumonia. Direct examination of BAL fluid was also used to identify cells with intracellular organ isms. Ventilator-associated pneumonia was diagnosed in 18 patients; a total of 39 microorganisms were recovered from BAL fluid and 29 from P SB specimens. Cultures of 21 BAL and 23 PSB specimens were sterile. Qu antitative BAL and PSB cultures coincided in 76 % of cases. Sterile BA L and PSB cultures agreed in 87 % of cases. Cultures were completely d iscordant in only three cases. The sensitivity of BAL for diagnosis of ventilator-associated pneumonia using bacterial counts of greater tha n or equal to 10(4) cfu/ml was 89 %, and specificity was 100 %. In 14 of the 18 patients with ventilator-associated pneumonia, the percentag e of cells containing intracellular organisms in specimens recovered b y BAL was 11.6 % versus 0.45 % in patients without pneumonia (p < 0.05 ). In the remaining four patients, all of whom had Pseudomonas aerugin osa pneumonia, no intracellular organisms could be detected. Using a c ut-off point of greater than or equal to 5 % of cells with intracellul ar organisms, the sensitivity and specificity for the early diagnosis of ventilator-associated pneumonia was 67 % and 96 %, respectively The results confirm the usefulness of the quantitative BAL culture (with a cut-off at 10(4) cfu/ml) for the diagnosis of ventilator-associated pneumonia. The identification of intracellular organisms in BAL fluid is a good early indicator of pneumonia, but the sensitivity of this te chnique may be lower for Pseudomonas aeruginosa infections.