The Differences in Cerebral Oxygenation Among Patients Undergoing Thyroidectomy in Different Positions and Comparison of Their Effects on Nausea-Vomiting

Abstract

Background: Hyperextension of the patient's neck associated with distortion and vasospasm of the vertebral and internal carotid arteries intra-operatively. In this study we aimed to investigation of whether there is effects of supine, slight neck hyperextension and semi-seated and neck hyperextension positions of patients on postoperative nausea and vomiting (PONV) via regional cerebral oxygen saturation (rSO(2)). Methods: ASA I-II group of 40 adult patients for whom elective thyroid operations under general anesthesia (GA) were planned, were divided into 2 randomized groups. The patients in the Group 1 were positioned in the hyperextension of the neck at 45 degrees semi-seated position and in the Group 2 patients were positioned in the supine position. Results: The heart rate (HR), and mean arterial pressure (MAP) values were found to be statistically significantly higher in the first group than the second group in a few values (p<0.05). There were no significant differences between the groups when they were compared for left and right cerebral oxygen saturation (p>0.05). No correlation was determined between the cerebral arterial desaturation and rates of PONV. Conclusions: It was concluded that cardiovascular changes due to hyperextension of the neck in a semi-seated position during surgery under general anesthesia, despite a cerebral desaturation in rSO(2) that remained within the cerebral auto-regulation range and there is no correlation of PONV with either neck hyperextension in the semi-seated position or desaturation conditions with less than a 20% decrease in rSO(2).