Ultrasound-guided versus conventional lung recruitment manoeuvres in thoracic surgery: a randomised controlled study

Lung recruitment manoeuvres (RMs) during mechanical ventilation may reduce atelectasis, however, the optimal recruitment strategy for patients undergoing thoracic surgery remains unknown. Our study was designed to investigate whether ultrasound-guided lung RMs is superior to conventional RMs in reducing perioperative atelectasis during thoracic surgery with one-lung ventilation. We conducted a randomised controlled clinical trial from August 2022 to September 2022. Sixty patients scheduled for video-assisted thoracoscopic surgery (VATS) under general anaesthesia were enrolled. Subjects were randomly divided into the ultrasound-guided RMs group (manual inflation guided by lung ultrasound) or conventional RMs group (manual inflation with 30 cmH2O pressure). Lung ultrasound were performed at three predefined time points (1 min after anaesthetic induction; after RMs at the end of surgery; before discharge from postanesthesia care unit [PACU]). The primary outcome was lung ultrasound score before discharge from the PACU after extubation. In the early postoperative period, lung aeration deteriorated in both groups even after lung RMs. However, ultrasound-guided lung RMs had significantly lower lung ultrasound scores when compared with conventional RMs in bilateral lungs (2.0 [0.8-4.0] vs. 8.0 [3.8-10.3], P < 0.01) at the end of surgery, which remained before patients discharged from the PACU. Accordingly, the lower incidence of atelectasis was found in ultrasound-guided RMs group than in conventional RMs group (7% vs. 53%; P < 0.01) at the end of surgery. Ultrasound-guided RMs is superior to conventional RMs in improving lung aeration and reducing the incidence of lung atelectasis at early postoperative period in patients undergoing VATS. The study protocol was approved by the Institutional Review Board of the Fudan University Shanghai Cancer Center (No. 220,825,810; date of approval: August 5, 2022) and registered on Chinese Clinical Trial Registry (registration number: ChiCTR2200062761).

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

Background

Postoperative 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.

Methods

In 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.

Results

From 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.

Conclusions

In 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.

Effects of ultrasound-guided alveolar recruitment manoeuvres compared with sustained inflation or no recruitment manoeuvres on atelectasis in laparoscopic gynaecological surgery as assessed by ultrasonography: a randomized clinical trial

Background

The majority of patients may experience atelectasis under general anesthesia, and the Trendelenburg position and pneumoperitoneum can aggravate atelectasis during laparoscopic surgery, which promotes postoperative pulmonary complications. Lung recruitment manoeuvres have been proven to reduce perioperative atelectasis, but it remains controversial which method is optimal. Ultrasonic imaging can be conducive to confirming the effect of lung recruitment manoeuvres. The purpose of our study was to assess the effects of ultrasound-guided alveolar recruitment manoeuvres by ultrasonography on reducing perioperative atelectasis and to check whether the effects of recruitment manoeuvres under ultrasound guidance (visual and semiquantitative) on atelectasis are superior to sustained inflation recruitment manoeuvres (classical and widely used) in laparoscopic gynaecological surgery.

Methods

In this randomized, controlled, double-blinded study, women undergoing laparoscopic gynecological surgery were enrolled. Patients were randomly assigned to receive either lung ultrasound-guided alveolar recruitment manoeuvres (UD group), sustained inflation alveolar recruitment manoeuvres (SI group), or no RMs (C group) using a computer-generated table of random numbers. Lung ultrasonography was performed at four predefined time points. The primary outcome was the difference in lung ultrasound score (LUS) among groups at the end of surgery.

Results

Lung ultrasound scores in the UD group were significantly lower than those in both the SI group and the C group immediately after the end of surgery (7.67 ± 1.15 versus 9.70 ± 102, difference, -2.03 [95% confidence interval, -2.77 to -1.29], P < 0.001; 7.67 ± 1.15 versus 11.73 ± 1.96, difference, -4.07 [95% confidence interval, -4.81 to -3.33], P < 0.001;, respectively). The intergroup differences were sustained until 30 min after tracheal extubation (9.33 ± 0.96 versus 11.13 ± 0.97, difference, -1.80 [95% confidence interval, -2.42 to -1.18], P < 0.001; 9.33 ± 0.96 versus 10.77 ± 1.57, difference, -1.43 [95% confidence interval, -2.05 to -0.82], P < 0.001;, respectively). The SI group had a significantly lower LUS than the C group at the end of surgery (9.70 ± 1.02 versus 11.73 ± 1.96, difference, -2.03 [95% confidence interval, -2.77 to -1.29] P < 0.001), but the benefit did not persist 30 min after tracheal extubation.

Conclusions

During general anesthesia, ultrasound-guided recruitment manoeuvres can reduce perioperative aeration loss and improve oxygenation. Furthermore, these effects of ultrasound-guided recruitment manoeuvres on atelectasis are superior to sustained inflation recruitment manoeuvres.

Trial registration

Chictr.org.cn, ChiCTR2100042731, Registered 27 January 2021, www.chictr.org.cn.

Comparison of the efficacy of two alveolar recruitment manoeuvres in improving the lung mechanics and the degree of atelectasis in anaesthetized healthy sheep

The aim of the present study was to evaluate whether the application of two types of alveolar recruitment manoeuvres (ARMs) followed by a positive end-expiratory pressure (PEEP) improved lung mechanics and the degree of atelectasis caused by general anaesthesia. Twenty-one female Merino sheep were divided into three groups: sustained inflation ARM (ARMsust), stepwise ARM (AMRstep), and control (without ARM). Sheep received detomidine-morphine for premedication, propofol for induction, and isoflurane during general anaesthesia in a volume-controlled mode with 100% oxygen during the first 15 min of anaesthesia and 40% the rest of the study. The right jugular vein and metacarpal artery were catheterised for mixed venous and arterial blood sample collection, respectively. The quasistatic compliance (Cqst), oxygenation parameters, and shunt fraction (Qs/Qt) were monitored before ARM application (TpreARM), and at 10 (T10) and 60 min (T60) after ARM application. A pulmonary histopathological study was conducted on five animals from each group. A significant increase in Cqst was observed in both ARM groups at T10 compared to TpreARM (ARMsust: P = 0.001; ARMstep: P = 0.002), although only the ARMsust group showed significant differences compared to the control group. The ARMstep group presented a significant improvement in oxygenation parameters and Qs/Qt fraction (T10: 4.84 (3.26-16.48)%, P = 0.048; T60: 4.40 (4.31-14.16)%, P = 0.004) compared with TpreARM (21.48 (20.61-28.32)%). The ARMstep group had the highest percentage of alveolar area and the most homogeneous values. In conclusion, the application of a stepwise ARM followed by PEEP improved atelectasis caused by isoflurane anaesthesia in healthy sheep.

Lung recruitment maneuvers: opening the door to a hidden enemy

Recruitment manoeuvres (RM) are common practice in anaesthesiology; however, they can have adverse effects. We present an unforeseen complication in a patient undergoing surgical resection of a bronchial tumour who presented cardiac arrest due to pulseless electrical activity immediately after RMs. A transoesophageal echocardiogram performed after return of spontaneous circulation showed a patent foramen ovale (PFO), left ventricular dysfunction with segmental changes, and air in the left ventricle, leading to suspicion of paradoxical air embolism. The contractility changes normalised spontaneously, and postoperative evolution was uneventful. RMs cause changes in intracavitary pressures that can lead to opening of a PFO (present in up to 30% of the population) and reversal of the physiological left-right shunt. Transoesophageal echocardiography facilitated immediate diagnosis and follow-up.

Recruitment manoeuvres in anaesthesia: How many more excuses are there not to use them?

Pulmonary recruitment manoeuvres (RM) are intended to reopen collapsed lung areas. RMs are present in nature as a physiological mechanism to get a newborn to open their lungs for the first time at birth, and we also use them, in our usual anaesthesiological clinical practice, after induction or during general anaesthesia when a patient is desaturated. However, there is much confusion in clinical practice regarding their safety, the best way to perform them, when to do them, in which patients they are indicated, and in those where they are totally contraindicated. There are important differences between RM in the patient with adult respiratory distress syndrome, and in a healthy patient during general anaesthesia. Our intention is to review, from a clinical and practical point of view, the use of RM, specifically in anaesthesia.