Ventilation with High or Low Tidal Volume with PEEP Does Not Influence Lung Function after Spinal Surgery in Prone Position: A Randomized Controlled Trial

Background: Spinal surgery in the prone position is accompanied by increased intrathoracic pressure and decreased respiratory compliance. This study investigated whether intraoperative lung protective mechanical ventilation improved lung function evaluated with pulmonary function tests in patients at risk of postoperative pulmonary complications (PPCs) after major spinal surgery in the prone position. Methods: Seventy-eight patients at potential risk of PPCs were randomly assigned to the protective group (tidal volume; 6 mL/kg predicted body weight, 6 cm H 2 O positive end-expiratory pressure with recruitment maneuvers) or the conventional group (10 mL/kg predicted body weight, no positive end-expiratory pressure). The primary efficacy variables were assessed by pulmonary function tests, performed before surgery, and 3 and 5 days afterward. Results: Postoperative forced vital capacity (2.17±0.1 L vs. 1.91±0.1 L, P=0.213) and forced expiratory volume in 1 second (1.73±0.08 L vs. 1.59±0.08 L, P=0.603) at postoperative day (POD) 3 in the protective and conventional groups, respectively, were similar. Trends of a postoperative decrease in forced vital capacity (P=0.586) and forced expiratory volume in 1 second (P=0.855) were similar between the groups. Perioperative blood-gas analysis variables were comparable between the groups. Patients in the protective and conventional groups showed similar rates of clinically significant PPCs (8% vs. 10%, P>0.999). Conclusions: In patients at potential risk of developing PPCs undergoing major spinal surgery, we did not find evidence indicating any difference between the lung protective and conventional ventilation in postoperative pulmonary function and oxygenation.