Brain oxygen supply-demand balance and cerebral autoregulatory plateau under propofol anesthesia and influencing factors

To investigate the differences in brain oxygen supply-demand balance before and after intravenous anesthesia with propofol, and determine the influencing factors of the balance and cerebral autoregulation plateau.

A total of 53 patients undergoing open hepatobiliary surgery in our hospital from June 2020 to October 2020 were enrolled in this study. Their local regional cerebral oxygen saturation (rSO₂), cerebral tissue hemoglobin concentration index (THI) and mean arterial pressure (MAP) were monitored and recorded from entering the operating room to the end of the operation. Brain oxygenation was assessed using rSO₂ as well as using THI. Then the moving linear Pearson correlation coefficient between rSO₂ and MAP was calculated and named as Cox, and the moving linear Pearson correlation coefficient between THI and MAP was also calculated and named as THx. The upper and lower limits and range of cerebral autoregulation (CA) were studied using COx and THx. Intermittent sampling of blood was performed for blood gas analysis. All patients underwent standardized anesthesia management.

There were significant differences in rSO₂ in the left and right brain before and after anesthesia (left: P<0.001, right: P<0.001), so were in THI in the left and right sides before and after anesthesia (left: P<0.001, right: P<0.001). There were no statistical differences in the left and right rSO₂ and THI among those at different ages, with the porta hepatis being blocked or not, and with different operation durations (P>0.05). Linear correlation curve showed that the THI values of the left and right brain were decreased with age (left: r=-0.261 8, P=0.058 3; right: r=-0.283 6, P=0.039 6). Under propofol intravenous anesthesia, COx defined the lower limit, upper limit and range of CA were 81.98±12.63, 93.67±13.69 and 11.22±8.38 mmHg, respectively. THx defined the lower limit, upper limit and range of CA was 79.96±10.61, 93.77±12.34 and 13.79±8.63 mmHg, respectively. No obvious differences were seen in the upper limit, lower limit and adjustment range of CA defined by COx and THx among those with the age is older than 50 years or not, porta hepatis being blocked or not, and longer than 360 min or not (P>0.05).

Propofol anesthesia can induce declined rSO₂ and THI values in the left and right brain. The left and right cerebral THI is affected by age, while the lower limit, upper limit and range of CA are not affected by the age older than 50 years, the porta hepatis being blocked or not, and the operation time longer than 360 min or not.