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
.