PNEUMONIA IN ACUTE RESPIRATORY-DISTRESS SYNDROME - A PROSPECTIVE EVALUATION OF BILATERAL BRONCHOSCOPIC SAMPLING

We evaluated the diagnostic yield of bilateral bronchoalveolar lavage (BAL) in patients with acute respiratory distress syndrome (ARDS) with suspected ventilator-associated pneumonia (VAP) and compared BAL resu lts from contralateral sites. Ninety-four ARDS patients with suspected VAP underwent 172 bronchoscopies (344 BALs). BAL was processed for qu antitative cultures, total cell count and subjected to microscopic ana lysis for cell differential, presence of intracellular organisms (ICO) , and Cram stain. The diagnostic threshold for VAP was a growth of gre ater than or equal to 10(4) cfu/ml in BAL culture. Most episodes (68%) had bilateral insignificant bacterial growth. Forty (43%) patients ha d one or more episodes of VAP. Thirty-three of the 55 (60%) positive b ronchoscopies had significant growth in only one side, 18 were right B AL, and 15 were left BAL. Episodes with bilateral significant growth w ere more likely to be polymicrobial, to have a bacterial growth greate r than or equal to 10(5) cfu/ml in the BAL, and to possess a higher pe rcentage of neutrophils and ICO. Among 65 microorganisms recovered in significant concentration, Pseudomonas aeruginosa occurred in 43% and S. aureus in 15%. Overall, Cram stain had a sensitivity of 54% and a s pecificity of 87%; and Giemsa stain (> 2% ICO) had a sensitivity of 46 % and a specificity of 93%. Antibiotic treatment was modified by the r esults of BAL cultures in 50 (91%) episodes of pneumonia. In patients with ARDS and suspected VAP, bilateral BAL quantitative bacterial cult ures had significant growth on one side only in 19% and in both sides in 13%.