# Role of Cerebral Oximetry in Reducing Postoperative End-Organ Dysfunction After Major Non-Cardiac Surgery: A Randomised Controlled Trial

## TL;DR

This study tested if monitoring brain oxygen levels during surgery could reduce postoperative complications but found no significant benefit.

## Contribution

A novel algorithm-based intervention to restore cerebral oxygen saturation during surgery was tested in a randomized controlled trial.

## Key findings

- Cerebral desaturation occurred in over 85% of patients during surgery.
- Algorithm-guided therapy restored brain oxygen levels in 86% of cases.
- No reduction in postoperative complications was observed between groups.

## Abstract

Background/Objectives: An increasing number of older individuals require general anaesthesia for major non-cardiac surgery, with 20% displaying postoperative complications. Regional cerebral oxygen saturation (rSO2) correlates with the gold standard of mixed venous oxygen saturation, indicating global perfusion. We hypothesised that rSO2-based anaesthesia reduces organ dysfunction and morbidity after major non-cardiac surgery. Methods: In Singapore and Toronto, we conducted a prospective, double-blind, randomised controlled trial in elderly patients undergoing major non-cardiac surgery, after obtaining research ethics board permission and informed consent. This RCT followed the CONSORT guidelines. Patients received bilateral cerebral oximetry sensors, and the control group received standard care. In the intervention group, an algorithm restored rSO2 if it dropped 10% below baseline for >15 s by adjusting cerebral perfusion pressure, inspired oxygen concentration, end-tidal carbon dioxide, depth of anaesthesia, haemoglobin, and cardiac index. Postoperative complications and outcomes were noted. Categorical data were analysed using Chi-square or Fisher’s exact tests and continuous data using a t-test or a Mann–Whitney U test. The study was powered for 394 patients, but due to the COVID-19 pandemic and funding constraints, this study was terminated at 101 patients. Results: Of 101 patients, 49 were randomised to the control and 52 to the intervention group. A total of 31 (63%) patients in the control group and 30 (58%) in the interventional exhibited bilateral cerebral desaturation. Time of cumulative cerebral desaturation was longer in the control group (23 ± 48 min vs. 9 ± 15 min, respectively, p = 0.01). A total of 142 algorithm-based treatments were employed, restoring rSO2 in 29 (86%) patients. Both groups displayed equal postoperative outcomes. Conclusions: In major non-cardiac surgery, cerebral desaturation is prevalent in over 85% of patients. Although algorithm-guided therapy restored rSO2 in the majority of patients, it did not result in reduced postoperative morbidity.