Effects of preconditioning with one-lung ventilation on perioperative oxygenation and oxidative stress in thoracoscopic surgery: a prospective single-center randomized controlled clinical trial

Hypoxemia is a common and clinically significant problem during one-lung ventilation (OLV). Prophylactic ventilation strategies to prevent OLV-associated hypoxemia and lung injury remain insufficiently defined. Patients scheduled for elective video-assisted thoracoscopic lung lobectomy or segmentectomy were enrolled and randomly assigned into a preconditioning group or a control group. After anesthesia induction, a visual double-lumen endotracheal tube was inserted. The preconditioning group underwent three cycles of OLV preconditioning protocol before surgery: 2 min OLV → 2 min two-lung ventilation (TLV) → 4 min OLV → 4 min TLV → 6 min OLV → 6 min TLV. The control group received conventional OLV only. Ventilation parameters: the tidal volume was set at 6 mL/kg during OLV and 8 mL/kg during TLV. Respiratory rate was adjusted to maintain an end-tidal carbon dioxide partial pressure of 35–45 mmHg. The primary outcome was the oxygenation index (arterial partial pressure of oxygen/fraction of inspired oxygen, PaO 2 /FiO 2 ). Secondary outcomes included perioperative oxidative stress markers and the incidence of postoperative pulmonary complications (PPCs) within 7 days after surgery. Seventy-four patients were included in the final analysis. The oxygenation index decreased in both groups after initiation of OLV, reaching its lowest value at 30 min. At this time point, the preconditioning group showed a significantly higher oxygenation index than the control group (209 ± 64 vs. 145 ± 43 mmHg, P < 0.001). No significant differences were observed between the two groups in perioperative superoxide dismutase (SOD) levels [168 ± 16 vs. 160 ± 21 U/mL, P = 0.302] or in the incidence of PPCs (10/38 vs. 16/36, P = 0.105). OLV preconditioning improved intraoperative oxygenation during thoracic surgery, but did not significantly affect perioperative oxidative stress or the incidence of PPCs. The study was retrospectively registered in the Chinese Clinical Trial Registry on April 8, 2021, ( http://www.chictr.org.cn , ChiCTR2100045203).