Use of Airway Pressure Release Ventilation is Associated With a Reduced Incidence of Ventilator-Associated Pneumonia in Patients With Pulmonary Contusion

Background: Past studies suggest that airway pressure release ventilation (APRV) is associated with reduced sedative requirements and increased recruitment of atelectatic lung, two factors that might reduce the risk for ventilator-associated pneumonia (VAP). We investigated whether APRV might be associated with a decreased risk for VAP in patients with pulmonary contusion. Materials: Retrospective cohort study. Results: Of 286, 64 (22%) patients requiring mechanical ventilation for > 48 hours met criteria for pulmonary contusion and were the basis for this study. Subjects with pulmonary contusion had a significantly higher rate of VAP than other trauma patients, [VAP rate contusion patients: 18.3/1,000, non-contusion patients: 7.7/1,000, incidence rate ratio 2.37 (95% confidence interval [CI], 1.11-4.97), p = 0.025]. Univariate analysis showed that APRV (hazard ratio, 0.15 [0.03-0.72; p = 0.018]) was associated with a decreased incidence of VAP. Cox proportional hazards regression, using propensity scores for APRV to control for confounding, supported a protective effect of APRV from VAP (hazard ratio, 0.10 [95% CI, 0.02-0.58]; p = 0.01). PaO2/FiO(2) ratios were higher during APRV compared with conventional ventilation (p < 0.001). Subjects attained the goal Sedation Agitation Score for an increased percentage of time during APRV (median [interquartile range (IQR)] 72.7% [33-100] of the time) compared with conventional ventilation (47.2% [0-100], p = 0.044), however, dose of sedatives was not different between these subjects. APRV was not associated with hospital mortality (odds ratio 0.57 [95% CI, 0.06-5.5]; p = 0.63) or ventilator-free days (No APRV 15.4 vs. APRV 13.7 days, p = 0.49). Conclusion: Use of APRV in patients with pulmonary contusion is associated with a reduced risk for VAP.