Effect of recruitment manoeuvres under lung ultrasound-guidance and positive end-expiratory pressure on postoperative atelectasis and hypoxemia in major open upper abdominal surgery: A randomized controlled trial

Abstract

BackgroundPostoperative pulmonary complications (PPCs) especially atelectasis and hypoxemia are common during abdominal surgery. Studies on the effect of either recruitment manoeuvres (RMs) or positive end-expiratory pressure (PEEP) on PPCs are controversial. The objective of this study is to evaluate the effect of perioperative lung ultrasound (LUS)-guided RMs combined with PEEP on the reduction of postoperative atelectasis and hypoxemia in major open upper abdominal surgery. MethodsIn this randomized controlled trial, 122 adult patients undergoing major open upper abdominal surgery were allocated into three groups: control (C) group (n = 42); PEEP (P) group (n = 40); RMs combined with PEEP (RP) group (n = 40). All patients were scheduled for general anaesthesia using the lung-protective ventilation (LPV) strategy. The levels of PEEP in the three groups were 0 cmH2O, 5 cmH2O and 5 cmH2O. LUS examination was carried out at 3 predetermined time points in each group: 5 min after intubation (T1), at the end of surgery (T2) and 15 min after extubation (T3). Patients with atelectasis on the sonogram in the RP group received LUS-guided RMs at point T2. LUS scores were used to estimate the severity of aeration loss. The P/F ratio (PaO2/FiO2) at 15min after extubation was used to assess the incidence of postoperative hypoxemia. Primary outcomes were the incidences of postoperative atelectasis and hypoxemia (PaO2/FiO2 < 300 mmHg). The secondary outcome was the distribution of LUS scores in each lung area. ResultsFrom July 2021 to December 2021, 122 consecutive patients were enrolled. No typical atelectasis was observed 5 min after intubation. The incidence of atelectasis was 52.4%, 50.0% and 42.5% in the C group, P group and RP group at the end of surgery, respectively. The rate of atelectasis in the C group, P group and RP group (after RMs) was 52.4%, 50.0% and 17.5%, respectively, 15 min after extubation (P < 0.01). The frequency of postoperative hypoxemia was 27.5%, 15.0% and 5.0% in the C group, P group and RP group, respectively (P < 0.017). The increased LUS scores mainly occurred in the superoposterior and inferoposterior quadrants at the end of surgery. Only in the RP group demonstrated a decreased LUS score in the posteriorquadrants after extubation. ConclusionsIn patients undergoing major open upper abdominal surgery, an intraoperative mechanical ventilation strategy without PEEP or with PEEP alone did not reduce PPCs. However, PEEP of 5 cmH2O combined with LUS-guided RMs proved feasible and beneficial to decrease the occurrence of postoperative atelectasis and hypoxemia in major open upper abdominal surgeries.