Effect of intravenous esketamine on oxygenation and intrapulmonary shunting during One-lung ventilation in thoracoscopic surgery: A Randomized Controlled Trial

Background： One-lung ventilation (OLV) is a commonly used mechanical ventilation technique in open chest surgery, which can lead to serious complications.This study aims to investigate the effects of esketamine on oxygenation (PaO₂/FiO₂) and intrapulmonary shunt (Qs/Qt) during OLV in patients undergoing thoracic surgery. Methods： Fifty patients were randomly allocated to either esketamine group (group E) or control group (group C).Group E received 0.5 mg/kg esketamine.The control group received normal saline. blood samples were takento analyze arterial blood gasses during four time periods at bfore anesthesia induction (T0),30 min after OLV(T1),60 min after OLV(T2) and 20 min after reinstitution of two-lung ventilation(T3).PaO₂/FiO₂, Qs/Qt , heart rate, mean arterial pressure(MAP),parameters mechanics and postoperative pulmonary complication incidence values were recorded at these time points. Results: Compared with the group C, the PaO2/FiO2 ratio was significantly increased, and the Qs/Qt were significantly decreased in the group E at T1, T2, and T3 (all p<0.05).At T1 and T2, the Ppeak and Pplat in the group E were significantly lower than those in the group C, while the Cdyn value was significantly higher than that in the group C (all P < 0.05).The incidence of atelectasis in the group E was significantly lower than that in the group C (16% vs. 32%, P=0.002). However, there was no statistically significant difference in the incidence of any other PPCs episodes between the two groups. Conclusion： Intravenous administration of esketamine during lung resection improves oxygenation status (PaO₂/FiO₂), reduces pulmonary artery shunt fraction (Qs/Qt), enhances pulmonary artery compliance (Cdyn), and decreases the incidence of postoperative pulmonary complications. Trial registration： The trial was registered at the Chinese Clinical Trials Registry (www.chictr.org.cn, registration number: ChiCTR2400093592, date of registration: 09/12/2024).