Positive-end expiratory pressure reduces incidence of ventilator-associated pneumonia in nonhypoxemic patients

Abstract

Objective: To analyze the effect on clinical outcomes of prophylactic positive end expiratory pressure in nonhypoxemic ventilated patients.

Design: Multicenter randomized controlled clinical trial.

Setting: One trauma and two general intensive care units in two university hospitals.

Patients: One hundred thirty-one mechanically ventilated patients with normal chest radiograph and PaO2/FiO2 above 250.

Interventions: Patients were randomly allocated to receive mechanical ventilation with 5-8 cm H2O of positive end-expiratory pressure (PEEP) (PEEP group, n = 66) or no-PEEP (control group, n = 65).

Measurements and main results: Primary end-point variable was hospital mortality. Secondary outcomes included microbiologically confirmed ventilator-associated pneumonia, acute respiratory distress syndrome, barotrauma, atelectasis, and hypoxemia (PaO2/FiO2 <175). Both groups were similar at randomization in demographic characteristics, intensive care unit admission diagnoses, severity of illness, and risk factors for ventilator-associated pneumonia. Hospital mortality rate was similar (p = 0.58) between PEEP (29.7%) and control (25.4%) groups. Ventilator-associated pneumonia was detected in 16 (25.4%) patients in the control group and 6 (9.4%) in the PEEP group (relative risk, 0.37; 95% confidence interval = 0.15-0.84; p = 0.017). The number of patients who developed hypoxemia was significantly higher in the control group (34 of 63 patients, 54%) than in the PEEP group (12 of 64, 19%) (p < 0.001), and the hypoxemia developed after a shorter period (median [interquartile range]) in the control group than in the PEEP group (38 [20-70] hrs vs. 77 [32-164] hrs, p < 0.001). Groups did not significantly differ in incidence of acute respiratory distress syndrome (14% in controls vs. 5% in the PEEP group, p = 0.08), barotrauma (8% vs. 2%, respectively, p = 0.12), or atelectasis (27% vs. 19%, respectively, p = 0.26).

Conclusions: These findings indicate that application of prophylactic PEEP in nonhypoxemic ventilated patients reduces the number of hypoxemia episodes and the incidence of ventilator-associated pneumonia.