Abstract
BackgroundAlthough the intraoperative alveolar recruitment maneuver (RM) efficiently treats atelectasis, the effect of Fio2 on atelectasis during RM is uncertain. We hypothesized that a high Fio2 (1.0) during RM would lead to a higher degree of postoperative atelectasis without benefiting oxygenation when compared to low Fio2 (0.4).MethodsIn this randomized controlled trial, patients undergoing elective laparoscopic surgery in the Trendelenburg position were allocated to low- (Fio2 0.4, n = 44) and high-Fio2 (Fio2 1.0, n = 46) groups. RM was performed 1-min post tracheal intubation and post changes in supine and Trendelenburg positions during surgery. We set the intraoperative Fio2 at 0.4 for both groups and calculated the modified lung ultrasound score (LUSS) to assess lung aeration after anesthesia induction and at surgery completion. The primary outcome was modified LUSS at the end of the surgery. The secondary outcomes were the intra- and postoperative Pao2 to Fio2 ratio and postoperative pulmonary complications.ResultsThe modified LUSS before capnoperitoneum and RM (P = 0.747) were similar in both groups. However, the postoperative modified LUSS was significantly lower in the low Fio2 group (median difference 5.0, 95% CI 3.0–7.0, P < 0.001). Postoperatively, substantial atelectasis was more common in the high-Fio2 group (relative risk 1.77, 95% CI 1.27–2.47, P < 0.001). Intra- and postoperative Pao2 to Fio2 were similar with no postoperative pulmonary complications. Atelectasis occurred more frequently when RM was performed with high than with low Fio2; oxygenation was not benefitted by a high-Fio2.ConclusionsIn patients undergoing laparoscopic surgery in the Trendelenburg position, absorption atelectasis occurred more frequently with high rather than low Fio2. No oxygenation benefit was observed in the high-Fio2 group.Trial registrationClinicalTrials.gov, NCT03943433. Registered 7 May 2019,
Highlights
The intraoperative alveolar recruitment maneuver (RM) efficiently treats atelectasis, the effect of FIO2 on atelectasis during RM is uncertain
Compression of basal lung regions due to a stiffened diaphragm would accelerate the formation of atelectasis that was already initiated during anesthesia induction [4]
One-hundred-and-seventy-eight patients scheduled to undergo laparoscopic surgery in the Trendelenburg position were assessed for eligibility
Summary
Design This prospective, patient- and sonographer-blinded, single-center, parallel, randomized, controlled trial was approved by the Institutional Review Board of Seoul National University Hospital (No 1903–137-1020, 22 April 2019) and registered at ClinicalTrials.gov (NCT03943433, 7 May 2019). Patients were randomly assigned to two groups based on the applied FIO2 during RM, in a 1:1 ratio, by computer-generated randomization, using R software (version 3.5.1, R Foundation for Statistical Computing, Vienna, Austria). Lung ultrasound examination and RM strategy Lung ultrasound examination was performed at three time-points: 1 min after starting mechanical ventilation, at the end of surgery (before emergence), and after breathing room air for 20 min at PACU (Fig. 1). Postoperative atelectasis, pneumonia, acute respiratory distress syndrome, and pulmonary aspiration data were collected by reviewing medical records Their severity was evaluated based on previous consensus definitions for standardized perioperative pulmonary complications [22]. Statistical analysis In our pilot study on patients undergoing laparoscopic surgery in the Trendelenburg position (n = 10), the modified LUSS [mean (SD)] before and at the end of surgery were 3.88 (1.26) and 8.66 (2.82), respectively.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
