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 endexpiratory pressure (standard ventilation strategy) or tidal volumes of 7 ml/kg ideal body weight, 10 cm H 2 O 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. What We Already Know about This Topic • The use of large tidal volumes during mechanical ventilation of the lungs can injure the lungs of critically ill patients What This Article Tells Us That Is New • A prospective, randomized, open-label trial of protective ventilation in 56 patients undergoing more than 2 h of open abdominal surgery showed that lower tidal volumes, positive end-expiratory pressure, and recruitment maneuvers led to significantly improved pulmonary function test results up to 5 days after surgery, fewer chest x-ray findings and improved Clinical Pulmonary Infection Scores ◆ This article is accompanied by an Editorial View. Please see: Vidal Melo MF, Eikermann M: Protect the lungs during abdominal surgery: It may change the postoperative outcome.

Protective Lung Ventilation During General Anesthesia: Is There Any Evidence?

“…However, these studies demonstrated that this mode of ventilation is feasible in open abdominal surgery with no adverse eff ects [23], [25]. In contrast to the previous studies, Severgnini et al, comparing a lung protective mechanical ventilation consisting of a V T of 7 ml/kg ideal body weight with PEEP levels of 10 cmH 2 O and recruitment maneuvers versus a V T of 9 ml/kg without PEEP, showed benefi cial eff ects of the lung-protective strategy during general anesthesia lasting more than 2 hours [26]. Th e lung-protective strategy improved postoperative respiratory function in terms of dynamic spirometry, oxygenation, and pulmonary complications for up to 5 days after surgery, without increasing the incidence of intraoperative complications.…”

“…Th e lung-protective strategy improved postoperative respiratory function in terms of dynamic spirometry, oxygenation, and pulmonary complications for up to 5 days after surgery, without increasing the incidence of intraoperative complications. Although there was no signifi cant diff erence in the hospital length of stay between groups, 20 % of the patients in the lungprotective group, compared with 40 % in the control group, were still in hospital on postoperative day 14 [26]. A recent multicenter randomized clinical trial in which lung-protective ventilation with a V T of 6-8 ml/kg predicted body weight, PEEP 6-8 cmH 2 O and recruitment maneuvers repeated every 30 minutes was compared with non-protective ventilation with V T 10-12 ml/kg without PEEP, found that the lung-protective ventilation signifi cantly reduced major pulmonary and extrapulmonary complications from 27.5 % to 10.5 % [27].…”

“…In this study, all patients are ventilated with protective tidal volumes (in both groups, V T < 8 ml/kg predicted body weight) and randomly assigned to a lung-protective strategy with use of recruitment maneuvers and PEEP levels of 12 cmH 2 O or a conventional strategy without recruitment maneuvers and PEEP between 0 and 2 cmH 2 O [28]. If the results of this study confi rm those of the last two trials [27], [26], lung-protective strategies will be more widely applied in patients undergoing abdominal surgery [28].…”

Early Effect of Tidal Volume on Lung Injury Biomarkers in Surgical Patients With Healthy Lungs

“…Recent studies suggest intraoperative ventilation settings affect postoperative pulmonary outcomes 1,[9][10][11][12][13] . Many surgical patients undergo short-term ventilation with large V T (greater than 10 mL/kg predicted body weight [PBW]) 12,14 without negative consequences.…”

The Scientific Basis for Postoperative Respiratory Care

“…They found that using lower tidal volume, PEEP, and recruitment maneuvers resulted in significantly improved pulmonary function test results up to 5 days after surgery, fewer chest x-ray findings, and improved Clinical Pulmonary Infection Score. 22 These findings need to be replicated in a larger group of patients, but present unique options for preventing PPCs. Very recently, Futier et al demonstrated that the use of PEEP, recruitment, and low tidal volume during open abdominal surgery resulted in fewer PPCs, compared to tidal volume of 10 -12 mL/kg and no PEEP.…”