ELASTIN FIBERS AND THE DIAGNOSIS OF BACTERIAL PNEUMONIA IN THE ADULT-RESPIRATORY-DISTRESS-SYNDROME

Objective: It has been inferred from previous work that 40% potassium hydroxide preparations of lower respiratory tract secretions that demo nstrate elastin fibers have a 100% specificity and positive predictive value in diagnosing bacterial pneumonia in intubated, mechanically ve ntilated patients without the adult respiratory distress syndrome (ARD S). Our aim was to assess the specificity of 40% potassium hydroxide p reparations in diagnosing bacterial pneumonia in patients with ARDS an d suspected pneumonia. Design: Prospective, case-referral clinical stu dy, Setting: Referral hospital, Patients: Of 24 patients with ARDS who were intubated and mechanically ventilated with suspected bacterial p neumonia, 22 were assessable and evaluated for this report. Interventi ons: Tracheo-bronchial aspirates were obtained from all patients and a nalyzed for elastin fibers using 40%,potassium hydroxide. Measurements and Main Results: Of the 22 assessable patients, ten patients did not have a complicating bacterial pneumonia, Six of these ten patients ha d potassium hydroxide preparations that demonstrated elastin fibers (f alse positives), The other four patients had preparations that did not demonstrate elastin fibers (true negatives). Specificity was 40%. Con clusion: Elastin fiber preparations are not specific for diagnosing ba cterial pneumonia in patients with ARDS.