The Impact of Higher Positive End Expiratory Pressure on Patient-Ventilator Asynchrony

Overview

Patient-ventilator asynchrony is known to frequently occur during lung protective ventilation in patients with ARDS. Previous clinical studies showed that patient-ventilator asynchrony was associated with worse outcome in ICU. Therefore, strategies to reduce patient-ventilator asynchrony need to be established promptly. Several asynchronies, e.g., breath stacking are caused by vigorous spontaneous breathing effort. Recently, the investigators' group found that higher positive end expiratory pressure (PEEP) reduced the intensity of spontaneous breathing effort of in severe ARDS model (rabbits, pigs) and patients with ARDS. Thus, the investigators conjectured that higher PEEP may reduce the intensity of spontaneous breathing effort and thereby reduce patient-ventilator asynchrony during protective ventilation strategy, compared with lower PEEP in patients with ARDS.

The cross-over study will enroll 10 participants fulfilled with the criteria of Berlin definition of moderate-to-severe ARDS and under mechanical ventilation in intensive care unit (ICU) at Osaka University Hospital. Informed consent will be obtained by legal representatives. After obtaining informed consent, participants will be randomly assigned to one of two groups: "higher PEEP - lower PEEP" or "lower PEEP - higher PEEP". PEEP, either higher or lower, will be set according to higher or lower PEEP/FIO2 table. The depth of sedation will be monitored quantitively and maintained to be the same throughout the protocol. The intensity of spontaneous breathing activity will be assessed with esophageal balloon manometry and electrical activity of diaphragm. At each PEEP setting, asynchrony index will be calculated.