Risk factors for late-onset ventilator-associated pneumonia in trauma patients receiving selective digestive decontamination

Objective: To determine the independent risk factors for late-onset ventilator-associated pneumonia (VAP) in trauma patients receiving selective digestive decontamination (SDD). Design: A 4-year, prospective cohort study of trauma patients meeting the following criteria: injury severity score > 15, and duration of mechanical ventilation > 5 days. Predictors of late-onset VAP occurrence were assessed by logistic regression analysis. Population: All patients received SDD consisting of polymixin E, gentamicin, and amphotericin B applied in nostrils, mouth, and gut with a 3-day course of parenteral cefazolin. VAP was suspected on clinical and radiological signs, and confirmed by the presence of at least one microorganism at a concentration of at least 10(4) CFU/ml on the broncho-alveolar lavage. Measurement: Independent risk factors for late-onset VAP. Results: A late-onset VAP was diagnosed in 90 (56%) out of 159 patients. Predicting factors for late-onset VAP were: use of non-depolarizing muscle relaxant agents for intubation [3.4 (CI 1.08 - 10.73)], duration of intubation [1.06 (CI 1.01 - 1.17)], length of intensive care unit (ICU) stay [1.05 ( CI 1.02 - 1.09)], and prior tracheal colonization [1.03 ( CI 1.02 - 1.21)]. Exposure to prior antimicrobial treatment, except SDD, conferred protection [0.3 (0.12 - 0.74)]. Conclusion: This study confirms the role of duration of intubation, length of ICU stay, and prior tracheal colonization in the development of late-onset VAP. The results also highlight the importance of the initial management on the development of late-onset VAP. The type of neuromuscular blocking agents to intubate trauma patients should be evaluated in future studies.