Procedures
The patient’s information was thoroughly reviewed by the surgeon and nurse before the start of the procedure. Intraoperative monitoring equipment, such as electrocardiogram, oxygen saturation, invasive arterial blood pressure, end-expiratory carbon dioxide, airway pressure, and entropy index, was also meticulously checked to ensure proper connections and functionality. The general anaesthesia approach typically involved a combination of inhalation and intravenous medications, comprising a bolus of propofol (1.5–2.5 mg/kg), rocuronium (0.6–0.8 mg/kg) and sufentanil (0.2–0.5 µg/kg). During the maintenance phase of anaesthesia, sevoflurane, remifentanil, and propofol were used. An appropriate double-lumen tracheal tube was selected based on the patient’s sex (37 for males and 35 for females). The positioning of the double-lumen endotracheal tube and bronchi was determined using fibreoptic bronchoscopy. Additional medications, such as rocuronium, were administered as required during the surgery. The target entropy index was maintained between 40 and 60 during the maintenance phase of general anaesthesia. Anaesthesiologists were given discretion in the use of analgesic pumps or peripheral nerve blocks when possible. Lactated Ringer’s solution was administered as the maintenance fluid at a rate of 3–5 mL/kg/h. Intraoperative vasoactive drugs were administered based on the mean arterial pressure, and routine postoperative antiemetic medications, such as glasnost, were administered.In this study, a standardised ventilation strategy was implemented for each patient. Tidal volume and respiratory rate were set at 6 mL/kg of predicted body weight and 13 breaths per minute, respectively, during OLV. Volume-controlled ventilation was employed with a 30% inspiratory pause and a 1:2 inspiratory to expiratory ratio. The inspired oxygen level was maintained at ≥ 60% and mixed with air. Predicted body weight (PBW) was calculated based on the patient’s sex, with PBW for men calculated as 50 + 0.91 × (height [cm] − 152.4) and PBW for women calculated as 45.5 + 0.91 × (height [cm] − 152.4). Oxygen concentration was increased as required to ensure adequate oxygenation during OLV and maintain a saturation level of at least 95%. After 5 min of OLV, the lowest driving pressure was determined, and PEEP was gradually increased from 0 to 10 cmH