EARLY DIAGNOSIS OF VENTILATOR-ASSOCIATED PNEUMONIA - IS IT POSSIBLE TO DEFINE A CUTOFF VALUE OF INFECTED-CELLS IN BAL FLUID

Study objective: To assess the usefulness of quantification of infecte d cells (ICs) in BAL fluid for the diagnosis of ventilator-associated pneumonia (VAP).Design: A prospective study. Setting: A medico-surgica l ICU in a tertiary health-care institution. Patients: One hundred thi rty-two patients (mean age, 52+/-19 years). The suspicion of nosocomia l pneumonia was strong in these patients: all had fever (greater than or equal to 38.5 degrees C), purulent tracheal aspirates, leukocytosis (greater than or equal to 10,000 cells per cubic millimeter), and new or persistent radiographic lung infiltrates. Interventions: One hundr ed sixty-three samples (BAL and protected specimen brushes [PSB]) were obtained. Results: VAP was present in 56 cases. The diagnosis was exc luded in the remaining 107 cases. The IC count was performed on 100 ce lls in BAL fluid. The percentage of IC was significantly higher (12.6/-12.4 vs 1.14+/-3.39; p<0.0001) in patients with pneumonia: the area under the receiver operating characteristic (ROC) curve was 0.888 and a threshold of 2% of IC corresponded to a sensitivity of 84%, a specif icity of 80%, a positive predictive value of 69%, a negative predictiv e value of 90%. Conclusions: It is possible to define a threshold of I C in BAL fluid with a good reliability by using an ROC curve. This tec hnique is useful for the early diagnosis (<2 h) of nosocomial bacteria l pneumonia in mechanically ventilated patients and allow a rapid and appropriate treatment of most of the patients with suspected VAP.