Change in stroke volume during alveolar recruitment maneuvers through transient continuous positive airway pressure or stepwise increase in positive end expiratory pressure in anesthetized patients: a prospective randomized double-blind study

Purpose Intraoperative alveolar recruitment maneuvers (ARM) used during protective ventilation strategy may have severe adverse hemodynamic effects, reported mainly during abrupt continuous positive airway pressure (CPAP). Stepwise increase and decrease in positive end expiratory pressure (PEEP) may be used. We compared the hemodynamic effects of these two maneuvers. Methods We enrolled patients scheduled for intermediate to high-risk surgery with continuous arterial pressure and stroke volume (esophageal Doppler) monitoring in a prospective, single-centre, randomized, double-blind study. After induction of anesthesia, we ensured preload independence of stroke volume before an ARM was randomly performed: 30 cm H 2 O CPAP for 30 sec (CPAP group) or stepwise increase in PEEP from 8 to 20 cm H 2 O with inspiratory pressure of 10 cm H 2 O followed by a stepwise decrease in PEEP from 20 to 8 cm H 2 O (STEP group). The primary outcome was the relative variation in stroke volume. Results Thirty-five patients were included in the CPAP and STEP groups. Mean (standard deviation) relative variation in stroke volume was −57 (24)% in the CPAP group and −32 (24)% in the STEP group (difference, −25; 95% confidence interval, −37 to −14; P < 0.001). Changes in systolic, mean, and diastolic arterial pressure over time were not different between groups. The ARM was stopped because of a systolic arterial pressure < 70 mm Hg in four patients in the CPAP group and in one patient in the STEP group. Conclusions Alveolar recruitment maneuvers through stepwise increase and decrease in PEEP have a better hemodynamic tolerance than transient CPAP. Trial registration ClinicalTrials.gov (NCT04802421); first submitted 15 March 2021.