Protective Mechanical Ventilation during General Anesthesia for Open Abdominal Surgery Improves Postoperative Pulmonary Function

Abstract

Background: The impact of intraoperative ventilation on postoperative pulmonary complications is not defined. The authors aimed at determining the effectiveness of protective mechanical ventilation during open abdominal surgery on a modified Clinical Pulmonary Infection Score as primary outcome and postoperative pulmonary function. Methods: Prospective randomized, open-label, clinical trial performed in 56 patients scheduled to undergo elective open abdominal surgery lasting more than 2 h. Patients were assigned by envelopes to mechanical ventilation with tidal volume of 9 ml/kg ideal body weight and zero-positive end-expiratory pressure (standard ventilation strategy) or tidal volumes of 7 ml/kg ideal body weight, 10 cm H2O positive end-expiratory pressure, and recruitment maneuvers (protective ventilation strategy). Modified Clinical Pulmonary Infection Score, gas exchange, and pulmonary functional tests were measured preoperatively, as well as at days 1, 3, and 5 after surgery. Results: Patients ventilated protectively showed better pulmonary functional tests up to day 5, fewer alterations on chest x-ray up to day 3 and higher arterial oxygenation in air at days 1, 3, and 5 (mmHg; mean ± SD): 77.1 ± 13.0 versus 64.9 ± 11.3 (P = 0.0006), 80.5 ± 10.1 versus 69.7 ± 9.3 (P = 0.0002), and 82.1 ± 10.7 versus 78.5 ± 21.7 (P = 0.44) respectively. The modified Clinical Pulmonary Infection Score was lower in the protective ventilation strategy at days 1 and 3. The percentage of patients in hospital at day 28 after surgery was not different between groups (7 vs. 15% respectively, P = 0.42). Conclusion: A protective ventilation strategy during abdominal surgery lasting more than 2 h improved respiratory function and reduced the modified Clinical Pulmonary Infection Score without affecting length of hospital stay.

Effect of protective ventilation on postoperative pulmonary complications in patients undergoing general anaesthesia: a meta-analysis of randomised controlled trials

“…The chest radiograph (X-rays) was used in all studies to detect atelectasis. Lung injury was diagnosed according to the American-European Consensus Conference definition in three studies,14 15 17 with no specific report in one study 16…”

Perioperative lung protective ventilation

“…An RCT in 40 patients having open abdominal surgery showed that compliance increased by 32% and airway resistance decreased by 21% for older patients undergoing open abdominal surgery with IOLPV compared with patients receiving conventional ventilation (P<0.001 and P=0.029, respectively) 88. A separate RCT found that patients receiving IOLPV performed better on spirometry than those receiving conventional ventilation as late as postoperative day 5 (mean forced expiratory volume in one second 1.63 (SD 0.55) v 1.23 (0.42) L/s, P<0.001; mean forced vital capacity 2.02 (0.52) v 1.57 (0.47) L/s, P<0.001) 89. More recently, several RCTs from the same group have found that IOLPV can decrease driving pressures for patients having abdominal surgery 7690…”

Recruitment maneuver in intraoperative mechanical ventilation: Possibility to prevent atelectasis open lung concept

“…21 Obuhvaćeno je 56 bolesnika sa otvorenom abdominalnom hirurgijom u trajanju od najmanje 2 sata. CPI skor (Clinical Pulmonary Infection Score: skor koji služi za brzu dijagnostiku pneumonija udruženih sa mehaničkom ventilacijom -VAP) 22 bio je niži kod bolesnika sa protektivnom ventilacijom pluća. Bolesnici sa ovim oblikom ventilacije imali su bolju arterijsku oksigenaciju i manji broj radiografski detektovanih promena na plućima.…”