Effect of Head Position on Cerebral Oxygen Saturation in Tympanoplasties Performed with Controlled Hypotensive Anesthesia.

Objective: Our goal was to examine the impact of head position, which had not been examined before, on cerebral oxygenation in tympanoplasties performed in the reverse Trendelenburg position during controlled hypotension. Methods: This prospective study was conducted in our clinic between July 2020 and November 2020. A total of 81 patients aged 18-59 years, who had an ASA physical condition classification score of 1-2 and were evaluated in two groups according to the type of surgery. In the tympanoplasty group, the head was turned to the contralateral ear and placed in minimal extension while in the septoplasty group, the head was kept in the neutral position. The regional cerebral oxygen saturation (c-rSO2) values of the right and left sides were recorded continuously with O3 regional oximetry probes on both sides throughout the operation. Results: When an overall examination was performed without separating the tympanoplasty group as right/left, the median oxygen saturation level was 69.50% (Q1:61.00-Q3:72.00) for the operated side and 74.00% (Q1:66.00-Q3:79.00) for the contralateral side. The oxygen saturation of the operated side was statistically significant lower (p<0.001). The median oxygen saturation of the operated side in the tympanoplasty group [69.50% (Q1: 61.00- Q3:72.00)] was statistically significantly lower than that of the septoplasty group [72.00% (Q1:65.25-Q3:77.75)] (p=0.004). Conclusion: This study showed that the rotation of the head 45° or above in the revers Trendelenburg supine position causes cerebral desaturation on the opposite side of rotation. [ABSTRACT FROM AUTHOR]