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

Abstract

For patients undergoing robot-assisted radical prostatectomy, the pneumoperitoneum with a steep Trendelenburg position could worsen intraoperative respiratory mechanics and result in postoperative atelectasis. We investigated the effects of individualized positive end-expiratory pressure (PEEP) on postoperative atelectasis, evaluated using lung ultrasonography. Sixty patients undergoing robot-assisted radical prostatectomy were randomly allocated into two groups. Individualized groups (n = 30) received individualized PEEP determined by a decremental PEEP trial using 20 to 7 cm H2O, aiming at maximizing respiratory compliance, whereas standardized groups (n = 30) received a standardized PEEP of 7 cm H2O during the pneumoperitoneum. Ultrasound examination was performed on 12 sections of thorax, and the lung ultrasound score was measured as 0–3 by considering the number of B lines and the degree of subpleural consolidation. The primary outcome was the difference between the lung ultrasound scores measured before anesthesia induction and just after extubation in the operating room. An increase in the difference means the development of atelectasis. The optimal PEEP in the individualized group was determined as the median (interquartile range) 14 (12–18) cm H2O. Compared with the standardized group, the difference in the lung ultrasound scores was significantly smaller in the individualized group (−0.5 ± 2.7 vs. 6.0 ± 2.9, mean difference −6.53, 95% confidence interval (−8.00 to −5.07), p < 0.001), which means that individualized PEEP was effective to reduce atelectasis. The lung ultrasound score measured after surgery was significantly lower in the individualized group than the standardized group (8.1 ± 5.7 vs. 12.2 ± 4.2, mean difference −4.13, 95% confidence interval (−6.74 to −1.53), p = 0.002). However, the arterial partial pressure of the oxygen/fraction of inspired oxygen levels during the surgery showed no significant time-group interaction between the two groups in repeated-measures analysis of variance (p = 0.145). The incidence of a composite of postoperative respiratory complications was comparable between the two groups. Individualized PEEP determined by maximal respiratory compliance during the pneumoperitoneum and steep Trendelenburg position significantly reduced postoperative atelectasis, as evaluated using lung ultrasonography. However, the clinical significance of this finding should be evaluated by a larger clinical trial.

Mechanical power during robotic-assisted laparoscopic prostatectomy: an observational study

“…When PEEP was individualized, resulting in levels between 12-14 cmH 2 O, arterial oxygenation and respiratory system compliance were higher compared to a lower fixed level (i.e. 5 cmH 2 O) [22,31,33,34]. However, in the same position, increasing PEEP to 10 cmH 2 O raised total mechanical power compared to 5 cmH 2 O of PEEP, although respiratory system elastance did not change.…”

Methods for Determination of Individual PEEP for Intraoperative Mechanical Ventilation Using a Decremental PEEP Trial

“…This leads to lower elastance of the respiratory system and consecutively improves oxygenation during surgery [28,30,31]. Many authors have advocated the individualization of PEEP in the operating room [32,33], and there is recent evidence that individualized PEEP is superior to a standardized "one PEEP fits all" strategy, even if higher PEEP levels are routinely used [7]. The optimal method for the choice of best PEEP during mechanical ventilation in the operating room is, however, less clear [34].…”

Positive end-expiratory pressure and risk of postoperative pulmonary complications in patients living at high altitudes and undergoing surgery at low altitudes: a single-centre, retrospective observational study in China

“…Currently, there are numerous studies on the association between intraoperative ventilator settings during general anaesthesia and the occurrence of PPCs. However, the reported results are still controversial, especially for different groups of patients and different types of surgery 18 26 27. Several randomised controlled trials showed that intraoperative ventilation with increased levels of PEEP (≥5 cmH 2 O) could prevent PPCs 28 29.…”

“…Several randomised controlled trials showed that intraoperative ventilation with increased levels of PEEP (≥5 cmH 2 O) could prevent PPCs 28 29. Moreover, some studies showed that individualised PEEP determined by maximal respiratory compliance significantly reduced postoperative atelectasis 13 18 27. Nonetheless, some other studies argued that PEEP did not show benefits for PPCs.…”