Regional cerebral oxygen saturation monitoring during spinal surgery in order to identify patients at risk for cerebral desaturation

Abstract

Background: Near infrared spectroscopy (NIRS) devices are non-invasive and monitor cerebral oxygen saturation (rScO2) continuously. NIRS interventional protocol is available in order to avoid hypoxic brain injury. Methods: We recruited patients scheduled for spinal surgery (n = 44). rScO2 was monitored throughout the surgery using INVOS 4100 cerebral oximeter. If the rScO2 values dropped more than 20% below baseline, or there was an absolute drop to below 50%, NIRS interventional protocol was followed. Results: In two patients rScO2 decreased by more than 20% from baseline values. In one patient rScO2 decreased to below 50%. NIRS protocol was initiated. As the first step, correct head position was verified-in one patient rScO2 increased above the threshold value. In the two remaining patients, mean arterial pressure was raised by injecting Ephedrin boluses as the next step. rScO2 raised above threshold. Patients with desaturation episodes had longer medium time of the operation (114 ± 35 versus 200 ± 98 min, p = 0.01). Pearson's correlation showed a negative correlation between rScO2 and duration of operation (r = 0.9, p = 0.2). Receiver operating characteristic curve analysis showed blood loss to be a strong predictor for possible cerebral desaturation (Area under the curve (AUC): 0.947, 95%CI: 0.836-1.000, p = 0.04). Conclusion: Patients with higher blood loss might experience cerebral desaturation more often than spinal surgery patients without significant blood loss.