Association between intraoperative cerebral desaturation detected by near-infrared spectroscopy and early...

The Trendelenburg position and pneumoperitoneum cause cardiovascular, cerebrovascular, metabolic, and respiratory changes. This preliminary study aimed to evaluate the effects of the Trendelenburg position and pneumoperitoneum on cerebral tissue oxygen saturation (rSO₂) and their association with early postoperative cognitive changes in patients undergoing laparoscopic major abdominal oncological surgery.

This preliminary exploratory study included 55 patients scheduled for elective laparoscopic major abdominal cancer surgery. Preoperative cognitive status was assessed using the Mini-Mental Test (MMT). Intraoperatively, regional cerebral oxygen saturation (rSO₂) was monitored using near-infrared spectroscopy (NIRS). Cerebral desaturation was defined as a decrease of ≥20% from baseline rSO₂ lasting at least 15 seconds. Hemodynamic parameters, pneumoperitoneum pressure, and Trendelenburg angle were recorded. Hemodynamic parameters and rSO₂ were recorded at 16 predefined time points: baseline (T0), after preoxygenation (T-preox), after induction (T-postind), after CO₂ insufflation (Ti), after Trendelenburg position (Tt), and every 20 minutes intraoperatively. Cognitive function was re-evaluated using the MMT one week postoperatively. Early postoperative cognitive change was defined as either a decrease of 2 or more points in the postoperative day 7 MMT score compared with baseline, or a postoperative MMT score of 23 and below.

A significant decrease in rSO₂ was observed after pneumoperitoneum and the Trendelenburg position. Patients were divided into two groups: those with a >20% decrease in rSO₂ (Group 2, n=6) and those without (Group 1, n=47). Group 2 had significantly lower median rSO₂ values at baseline and most intraoperative time points compared to Group 1 (p<0.05), which may be related to underlying cardiac comorbidities. The incidence of early postoperative cognitive changes was 11.3% (6/53 patients). All patients in Group 2 (100%) developed early postoperative cognitive changes, compared to 17% in Group 1 (p=0.002).Postoperative MMT scores were significantly lower in Group 2 (22.6 ± 2.2 vs. 26.1 ± 2.4, p=0.002). A negative correlation was found between postoperative MMT scores and age, ASA score, and comorbidity (p<0.05).

In conclusion, although the Trendelenburg position and pneumoperitoneum are generally expected to increase cerebral oxygenation, this may not be evident in high-risk patients with cardiac compromise. In this specific population, these factors may pose a significant risk for cerebral desaturation and appear associated with early postoperative cognitive changes. Therefore, monitoring rSO₂ using NIRS should be considered a beneficial tool for identifying vulnerable patients and potentially reducing the risk of cognitive decline.

Clinical Trial: NCT04714346.