Abstract: Objective To analyze the effects of different anesthesia depths on the cerebral oxygen metabolism indexes in patients undergoing brain surgery. Methods A total of 150 patients undergoing brain surgery in our hospital during Sep. 2018 and Sep. 2019 were randomized into 3 groups, with 50 patients in each group. The narcotrend index(NTI)was 47-56, 37-46, and 27-36, respectively, in groups A, B and C. The narcotrend stage(NTS)was D1, D2, and E0, respectively, in groups A, B and C. During the operation, intravenous anesthesia was induced and maintained, propofol was used to adjust and maintain different anesthesia depths, and the amounts of anesthetic drugs used in each group were recorded. The blood rheology and cerebral oxygen metabolism indicators of each group were measured before anesthesia induction(T0), before tracheal intubation(T1), immediately after tracheal intubation(T2), start of surgery(T3), end of surgery(T4)and extubation(T5). Data collected were analyzed with two-factor analysis of variance. Results (1) Anesthetic drugs and dosages: among propofol, remifentanil, and cisatracurium besilate, only the average dosage of propofol had a statistically significant difference among the 3 groups, and the dosage increased as the depth of anesthesia increased(1294.88±37.45, 1354.8±44.56, 1589.02±43.81, F=682.810, P<0.001). (2) Hemorheological indexes: the mean arterial pressure(MAP)and heart rate(HR)decreased with the depth of anesthesia. As the time of anesthesia prolonged, MAP showed an upward trend in group A, and a downward trend in groups B and C; HR showed an upward trend in group A, and an upward trend and then a downward trend in groups B and C(P<0.05). (3) Cerebral oxygen metabolism indexes: as the depth of anesthesia increased, the measured values of jugular bulb venous oxygen saturation(SjvO₂)and arterial oxygen content(CaO₂)showed an upward trend, while the measured values of difference of arteriovnous oxygen(Da-jvO₂), cerebral oxygen extraction ratio(CERO₂)and arterial blood oxygen partial pressure(PaO₂)showed a downward trend; as the time of anesthesia prolonged, the measured values of SjvO₂, CaO₂ and PaO₂ showed an upward trend, while the measured values of Da-jvO₂ and CERO₂ showed a downward trend(P<0.05). Conclusion D1, D2 and E0 depths of anesthesia can maintain a stable state of intraoperative hemodynamics in patients with cerebral surgery, promote the relatively stable balance of cerebral oxygen supply and brain metabolism within the compensation range. Deep anesthesia program can reduce the degree of brain tissue damage and intraoperative cerebral oxygen metabolism imbalance.

Key words: Depth of anesthesia, Brain surgery, Cerebral oxygen metabolism, Hemorheology