Effect of positive end-expiratory pressure on risk of microaspiration and ventilator-associated pneumonia in mechanically ventilated ICU patients: a prospective study.

backgroundVentilator-associated pneumonia (VAP) is a major contributor to morbidity and mortality in critically ill patients receiving mechanical ventilation. Microaspiration of subglottic secretions has a pivotal role in VAP pathogenesis, yet the optimal positive end-expiratory pressure (PEEP) for preventing microaspiration has not been extablished.

methodsThis prospective, single-center study determined the impact of different PEEP levels on microaspiration in 90 mechanically ventilated patients. Participants were stratified into three groups based on PEEP levels (0-3 cmH₂O, 4-6 cmH₂O, and 7-10 cmH₂O). Primary outcomes included biomarkers, such as pepsin concentration in airway secretions, and the incidence of microaspiration. Secondary outcomes assessed subglottic secretion volume, mechanical ventilation duration, and ICU length of stay.

resultsHigher PEEP levels (4-6 cmH₂O and 7-10 cmH₂O) were associated with significantly lower microaspiration rates and pepsin concentrations in airway secretions compared to the lowest PEEP group (0-3 cmH₂O; P < 0.05). Patients in the higher PEEP groups exhibited reduced total subglottic secretion volumes over 7 d and a shorter duration of mechanical ventilation. Group C (7-10 cmH₂O) demonstrated the most pronounced benefits with respect to microaspiration. No significant differences were observed in the duration of ICU stay among the groups.

conclusionElevated PEEP levels, especially within the 7-10 cmH₂O range, effectively reduce microaspiration, minimize subglottic secretion leakage, and shorten the duration of mechanical ventilation. These findings highlight the clinical importance of higher PEEP settings in reducing VAP risk and improving patient outcomes.