Effects of prone positioning on cerebral oxygenation in patients undergoing spine surgery under general anaesthesia

Under general anaesthesia, the impact of body positioning on different organs is mostly determined by the subsequent changes in the cardiovascular system, which are monitored with standard monitors. However, there is no objective method of neuromonitoring, therefore impacts on brain homeostasis are mainly conjectural. Near-infrared spectroscopy is a non-invasive method for monitoring tissue cerebral oxygenation. In this study, we aimed to observe the effects of the prone position on cerebral oxygenation in patients under general anaesthesia.

The study involved 44 patients undergoing spine surgeries in a prone position under general anaesthesia. Regional oxygen saturation readings were initially taken in the supine position and monitored continuously after transitioning to the prone position. A decrease in regional oxygen saturation of more than 20% was considered clinically significant.

A significant drop in blood pressure (p = 0.02) and heart rate (p = 0.04) was observed after positioning patients prone under general anaesthesia. In addition, end-tidal carbon dioxide levels rose notably after 30 min in the prone position (p = 0.017). Importantly, while no significant differences were found in cerebral oxygenation between the supine and prone positions, one patient did experience right-sided vision loss postoperatively.

Using near-infrared spectroscopy monitors is recommended for patients with comorbidities and those undergoing surgeries with extended durations in the prone position.