Intraoperative Oxygen Concentration and Postoperative Delirium After Laparoscopic Gastric and Colorectal Malignancies Surgery: A Randomized, Double-Blind, Controlled Trial

PURPOSE: Postoperative delirium (POD) is common in elderly patients undergoing laparoscopic surgery for gastric and colorectal malignancies. POD may be affected by different fraction of inspired oxygen (FiO(2)). The purpose of this study was to compare the effects of different FiO(2) on POD. PATIENTS AND METHODS: A randomized, double-blind controlled trial was performed in Qingdao Municipal Hospital Affiliated to Qingdao University. A total of 662 patients aged 65 to 85 years old underwent isolated laparoscopic radical gastrectomy, radical resection of colon cancer, or radical resection of rectal cancer only. A random number table method was used to divide the patients into two groups: 40% FiO(2) (group A) and 80% FiO(2) (group B). The primary endpoint was the incidence of POD, which was assessed by the Confusion Assessment Method (CAM) twice daily during the first 7 postoperative days, and POD severity was measured by the Memorial Delirium Assessment Scale (MDAS). The secondary endpoints were the intraoperative regional cerebral oxygen saturation (rSO(2)), Bispectral (BIS) index, invasive arterial blood pressure (IABP), oxygen saturation (SpO(2)), end-tidal carbon dioxide partial pressure (P(ET)CO(2)), the number of atelectasis cases and visual analogue scale (VAS) scores on days 1–7 after surgery. RESULTS: The incidence of POD was 19.37% (122/630), including 20.38% (64/314) in group A and 18.35% (58/316) in group B. No statistical significance was found in the incidence of POD between the two groups (P > 0.05); compared with group B, SpO(2), rSO(2) and PaO(2) decreased at T(2) to T(4) time point (P < 0.01), and the incidence of postoperative atelectasis decreased (P < 0.05) in group A. CONCLUSION: The incidence of POD was not significantly affected by different FiO(2) and the incidence of postoperative atelectasis was decreased at low FiO(2).