Intraoperative oxygen concentration and postoperative delirium in elderly patients undergoing major abdominal surgery: a prospective randomized controlled clinical trial.

Objective: Cerebral hypoxia and hypoperfusion are key pathophysiological contributors to postoperative delirium (POD). This study evaluated the impact of 40% versus 100% inspired oxygen (FiO₂) on POD incidence, neuroinflammation, and clinical outcomes in elderly patients undergoing major abdominal surgery.

Methods: In this trial, 160 elderly patients scheduled for major abdominal surgery under general anesthesia from 2022 to September 2023 were randomly assigned to receive 40% FiO₂ (n = 80) or 100% FiO₂ (n = 80). The primary outcome was POD incidence within 3 postoperative days. Secondary outcomes included perioperative oxygenation parameters, plasma neuroinflammatory markers, pulmonary infections, pain scores, and hospitalization duration. Blood samples were collected preoperatively and postoperatively for biomarker analysis.

Results: Among 154 analyzed patients, POD incidence was 5.2% (8/154), with no significant difference between 40% FiO₂ (6.4%, 5/78) and 100% FiO₂ (3.9%, 3/76) groups (P = 0.72). The 40% FiO₂ group exhibited lower saturation of pulse oxygen, regional cerebral oxygen saturation, and arterial partial pressure of oxygen from 1 h post-anesthesia (T2) to anesthesia end (T5) (P < 0.05). No intergroup differences in interleukin-6, tumor necrosis factor alpha, neuron-specific enolase, or neurofilament light chain levels were observed postoperatively (P > 0.05). FiO₂ levels did not influence pulmonary infection rates, postoperative VAS scores, or hospital stay (P > 0.05).

Conclusions: While 100% FiO₂ enhances cerebral oxygenation, it does not reduce POD incidence or neuroinflammatory markers compared to 40% FiO₂. High-concentration oxygen did not increase pulmonary complications but offered no clinical benefits in this cohort. Intraoperative FiO₂ should be titrated based on individualized patient needs.