Effects of intraoperative positive end-expiratory pressure optimization on respiratory mechanics and the inflammatory response: a randomized controlled trial

Abstract

Applying lung protective mechanical ventilation (LPV) during general anaesthesia even in patients with non-injured lungs is recommended. However, the effects of an individual PEEP-optimisation on respiratory mechanics, oxygenation and their potential correlation with the inflammatory response and postoperative complications have not been evaluated have not been compared to standard LPV in patients undergoing major abdominal surgery. Thirty-nine patients undergoing open radical cystectomy were enrolled in this study. In the study group (SG) optimal PEEP was determined by a decremental titration procedure and defined as the PEEP value resulting the highest static pulmonary compliance. In the control group (CG) PEEP was set to 6 cmH2O. Primary endpoints were intraoperative respiratory mechanics and gas exchange parameters. Secondary outcomes were perioperative procalcitonin kinetics and postoperative pulmonary complications. Optimal PEEP levels (median = 10, range: 8-14 cmH2O), PaO2/FiO2 (451.24 ± 121.78 mmHg vs. 404.15 ± 115.87 mmHg, P = 0.005) and static pulmonary compliance (52.54 ± 13.59 ml cmH2O-1 vs. 45.22 ± 9.13 ml cmH2O-1, P < 0.0001) were significantly higher, while driving pressure (8.26 ± 1.74 cmH2O vs. 9.73 ± 4.02 cmH2O, P < 0.0001) was significantly lower in the SG as compared to the CG. No significant intergroup differences were found in procalcitonin kinetics (P = 0.076). Composite outcome results indicated a non-significant reduction of postoperative complications in the SG. Intraoperative PEEP-optimization resulted in significant improvement in gas exchange and pulmonary mechanics as compared to standard LPV. Whether these have any effect on short and long term outcomes require further investigations. Trial registration: Clinicaltrials.gov, identifier: NCT02931409.

The Effect of Ventilation with Individualized Positive End-Expiratory Pressure on Postoperative Atelectasis in Patients Undergoing Robot-Assisted Radical Prostatectomy: A Randomized Controlled Trial

“…The combined effects of pneumoperitoneum and a steep Trendelenburg position could be synergistic [ 29 ]. The optimal PEEP of the individualized group was slightly higher than the levels of individualized PEEPs in previous studies conducted in patients undergoing open abdominal or laparoscopic surgery [ 13 , 30 , 31 ]. This may be ascribed to the combined effect of high intra-abdominal pressure and a steep Trendelenburg position, suggesting that greater PEEP would be needed for patients under this condition than for those undergoing open or laparoscopic surgery.…”

“…PEEP titrated using electrical impedance tomography reduced postoperative atelectasis [ 36 ] and improved intraoperative oxygenation [ 37 ]. Individualized PEEP determined by maximizing lung compliance, which was also used in the present study, improved oxygenation and respiratory mechanics [ 11 , 13 ]. In terms of the simplicity of implementation, this could be a chief and practical substitute for titrating an individualized PEEP compared to electrical impedance tomography.…”

“…Although there is accumulating evidence that the levels of PEEP should be individualized during the surgery, rather than setting a uniformly fixed PEEP, the optimal level of PEEP and how to individualize PEEP remain arguable [ 10 ]. According to previous studies [ 11 , 12 , 13 ], determining individualized PEEP according to maximal respiratory compliance is simple and shows promising results.…”

Individualized positive end-expiratory pressure (PEEP) during one-lung ventilation for prevention of postoperative pulmonary complications in patients undergoing thoracic surgery

“…[ 36 ] The optimum PEEP is the PEEP level that results in the greatest respiratory system compliance. [ 37 , 38 ] In the absence of previous lung injury, mechanical ventilation can destroy the fragile intercellular matrix structure of the lung. [ 39 ] General and local ischemia-reperfusion induced by hypotension, and hypoperfusion, surgical intervention, intraoperative blood loss, as well as tissue trauma itself, might lead to the release of inflammatory mediators and spread of bacteria that can prime the lungs further to the stress of mechanical ventilation.…”

What is new in respiratory monitoring?

“…And as in the case of ARDS, oxygenation and lung compliance are key parameters that bear on the efficacy and safety of mechanical ventilation during surgery. Ruszkai et al[ 17 ] titrated PEEP by finding the patient-specific values that maximized lung compliance when PEEP was decremented in small steps from 14 cmH 2 O. The optimum PEEP levels, which ranged from 8 to 14 cmH 2 O, were pitted against a fixed level of 6 cmH 2 O in 39 patients receiving cystectomy.…”