Regional Cerebral Oxygenation Changes Monitored with Near Infrared Spectroscopy Device During Spinal Neurosurgery in Prone Position and Postoperative Cognitive Dysfunction
Authors: Murniece Sniedze , Vanags Indulis , Mamaja Biruta 
Published: July 2018

Summary

Introduction. The adverse effects of hypoxia are well known, especially regarding the brain, and can lead to postoperative cognitive disturbances. On the other hand, the brain is still one of the least monitored organs intraoperatively. Near infrared spectroscopy devices are non-invasive continuous cerebral oxygenation monitoring devices that can also be used intraoperatively.
Prone position used during spinal neurosurgery is of particular importance regarding physiological changes that can occur in the human body and can lead to reduced blood and oxygen supply of the brain.

Aim of the Study. The aim of the study was to determine whether prone position used during spinal neurosurgery impacts cerebral oxygenation and patients’ cognitive performance after the surgery.

Material and methods. 40 patients were included in the study (32 study group, 8 control group). Patients were scheduled for spinal neurosurgery in prone position. All patients received standard general anaesthesia. In the study group regional cerebral oxygen saturation (rScO2) was continuously monitored using INVOS 4100 near infrared spectroscopy device. During the surgery every 5 minutes in study and control group medium non–invasive blood pressure, heart rate, peripheral oxygen saturation, exhaled CO2 and cerebral oxygenation measurements were fixed. We also fixed intraoperative blood loss and duration of the operation. Cognitive function was assessed in both groups using Montreal - Cognitive Assessment (MoCA) scale before surgery and two days after the surgery.

Results. We didn’t observe any significant changes in our calculated medium rScO2 intraoperative values. During induction of anaesthesia when patients were lying supine rScO2 above the right cerebral hemisphere was rScO2 72±9.7%, above the left cerebral hemisphere 71± 9.7%. Cerebral oxygen saturation in prone position was rScO2 R 74±10.7% and rScO2 L 74±10.1%. At the end of the surgery when patients were lying supine again rScO2 R was 74±9.3% and rScO2 L was 74±7.9%.
We didn’t observe any differences in medium MoCA scores when comparing study and control group. MoCA score before surgery in the study group was 24.1±2.9 points and 24.6±4.1 points in the control group. MoCA performed 2 days after the surgery was 24.6 ±3.2 points in study group and 24.6±2.4 points in control group.

Conclusions. No significant changes were observed in medium MoCA scores between patients who intraoperatively received noninvasive cerebral oxygen saturation monitoring and patients who did not receive it.
Despite medium calculated MoCA scores, individually we observed postoperative cognitive function impairment for MoCA 1-2 points in 5 out of 8 patients in the control group, but in the study group only 1 patient out of 32 showed cognitive dysfunction.
Intraoperative regional cerebral oxygen saturation monitoring can help to obviate cerebral desaturation that can lead to postoperative cognitive decline.