Positive end-expiratory pressure optimization with esophageal pressure during prone position in severe acute respiratory distress syndrome: a physiologic study

Abstract

Background: Protective ventilation [tidal volume at 6 ml/kg of predicted body weight, plateau pressure ≤ 30 cm H₂O, optimal positive end expiratory pressure (PEEP)] and prone position (PP) improved survival in acute respiratory distress syndrome (ARDS), PEEP improves alveolar recruitment but may generate overdistension, requiring specific monitoring. Esophageal pressure is used to estimate pleural pressure and to calculate the transpulmonary pressures. There are few data on PEEP variations and optimization during PP.

Objectives: To describe PEEP evolution through transpulmonary pressure monitoring during PP in severe ARDS patients.

Methods: Prospective observational study in severe ARDS needing prone positioning. An esophageal pressure catheter was placed in every patient to monitor transpulmonary pressure. The targets were an end-expiratory transpulmonary pressure (PLEE) between 0 and 2 cmH₂O and an end-inspiratory transpulmonary pressure (PLEI) < 25 cmH₂O. We described the evolution of ventilator parameters during PP.

Results: We included 35 patients with severe ARDS requiring prone positioning. Optimized PEEP decreased significantly during PP in the first eight hours then stabilized. We found significant interindividual variations. The transpulmonary pressures objectives were reached. PLEE measured before PEEP modification decreased significantly at H + 8.

Conclusion: Our study shows that optimized PEEP during PP varies mainly within the first 8 h. Monitoring transpulmonary pressures through an esophageal catheter throughout a PP session allows for PEEP optimization and ensures maximum recruitment and minimal overdistension.

Trial registration: RC 31/21/0514 - no 2021-A02752-39.

Keywords: ARDS; Esophageal pressure; PEEP; Prone position; Transpulmonary pressure.