The influence of Lung re-expansion at different time points on Respiratory mechanics and Postoperative Lung Atelectasis in Gynecological Laparoscopic Surgery

Author(s): Xiaoxia Wang, Suhong Chen, Zhipeng Guo, Jiang Feng, Wei Liu, Xiang Cui, Chunfang Yu, Taiman Huang.

Background: To investigate the effects of lung recruitment maneuver under lung ultrasound score (LUS) evaluation at different time points on respiratory mechanics and postoperative atelectasis during gynecological endoscopic surgery.

Methods: Sixty patients aged ≥ 18 years, with a BMI of<30 kg/m² and ASA I∼II, underwent elective gynecological endoscopic surgery from October 2021 to October 2022 were selected. The patients were divided into three groups using a random number table method, with 20 cases in each group: lung recruitment maneuver during pneumoperitoneum group (group A), lung recruitment maneuver after Trendlenburg position group (group B), and non-lung recruitment maneuver group (group C). Group A: Immediately after the set up of pneumoperitoneum, started the first lung recruitment maneuver (using PEEP incremental method for lung recruitment maneuver: Set the inspiratory pressure (Δ P) at 20cmH₂O in PCV mode, increased 5cmH₂O PEEP every 5 breaths to achieve a peak inspiratory pressure of 40cmH₂O, and kept the breathing for 10 times. Then, decreased 5cmH₂O PEEP every 5 breathing cycles until it reached the level before lung recruitment maneuver and changed to PCV-VG mode. Afterwards, the lung recruitment maneuver was performed once an hour. Group B: Immediately performed the first lung recruitment maneuver after the Trendlenburg position was set up. Afterwards, also by the PEEP incremental method, lung recruitment maneuver was performed once an hour. Group C: No lung recruitment maneuver throughout the entire process. Recorded the HR and MAP at the time points of establishing stable mechanical ventilation after intubation (T1), 5 minutes after pneumoperitoneum set up (T2), 5 minutes after Trendelenburg position set up (T3), 4 minutes after pneumoperitoneum cessation (T4), and 5 minutes after supine position set up (T5), and conducted blood gas analysis. Recorded PaO₂ and PaCO₂, calculated oxygenation index (OI) and intrapulmonary shunt rate (Qs/Qt; Qs/Qt=alveolar-arterial oxygen partial pressure difference × 0.0031/(alveolar-arterial oxygen partial pressure difference × 0.0031+5) × 100%). Recorded indicators of respiratory mechanics such as peak airway pressure (Ppeak), plateau pressure (Pplat), and dynamic lung compliance (Cdyn) from T1 to T5 and calculated Δ P; Recorded the LUS before anesthesia (T0), before tracheal catheter removal (T6), and 30 minutes after tracheal catheter removal (T7) and the occurrence of atelectasis. Recorded the incidence of pulmonary complications (atelectasis, pneumothorax, respiratory failure, aspiration pneumonia, respiratory infection, pleural effusion, bronchial asthma) in 3 days after operation.

Results: Compared with T0, the LUS of the three groups at T5 and T6 was significantly increased (P<0.05), while the LUS and the incidence of atelectasis in group C at T5 and T6 was significantly increased (P<0.05) compared to groups A and B. Compared with T1, Ppeak and Δ P of the three groups significantly increased while Cdyn significantly decreased at T2 to T5 (P<0.05). Compared group A with group B and C at T2, Ppeak and Δ P significantly decreased while Cdyn significantly increased (P<0.05); During T3- T5, compared between groups A, B and C, Ppeak and Δ P significantly decreased, while Cdyn significantly increased (P<0.05). There was no statistically significant difference between group A and B at T3. There was no statistically significant difference in the incidence of postoperative pulmonary complications among the three groups.

Conclusion: Protective ventilation after lung recruitment maneuver can improve respiratory mechanics and oxygenation during laparoscopic gynecological surgery, also is beneficial in terms of postoperative LUS and incidence of atelectasis.