Influential Factors Of EEG Bispectral Index During Cardiac Surgery With Cardiopulmonary Bypass

Objective: Aim of this study is to observe the effect of Cardiopulmonary bypass (CPB) which is used identical anaesthetic techniques on EEG Bispectral Index (BIS). Especially to observe a correlation between changes in BIS with factors other than anaesthetic technique (such as perfusion pressure, arterial pressure, venous pressure, temperature and blood gas analysis etc) it may provide theories according estimate cerebral function and awareness level during CPB.Methods: The 30 patients undergoing elective cardiac surgery with CPB, male 14, female 16, age 9.20 6.70 years old, weight 25.38 15.33 Kg. General anaesthetic was performed. Anaesthesia induction: midazolam 0.2 mg/ kg, etomidate 0.3 mg/ kg, fentany 6u g/ kg, succinylcholine 1.5~2.0 mg/kg. Anaesthesia was maintained with target-controlled infusions of midazolam 0.3mg/kg+fentany 50 g/ kg, before CPB and muscle relaxation was achieved with pipecuronium. Monitoring BIS is in the whole operation. Data of BIS, MAP, HR were recorded at 14 time-points: baseline (TO, anaesthesia induction (midazolam (T2), etomidate ( T3), fentany (T4), succinylcholine (T5)), tracheal intubation(T6), skin incision(T7), stemotomy (T8), aortic cannulation( T9), on CPB (T10), aortic cross-clamping ( T11), aortic declamping (T12), going off CPB (T13), skin closure(T14) and recorded data about perfusion pressure , perfusion quantum , mean arterial pressure (MAP), central venous pressure (CVP), nasopharyngeal temperature , rectal temperature during CPB at five time-points (on CPB, aortic cross-clamp, nadirtemperature, aorta declamp and rewarmed to 36 C. Data statistic analysis uses analysis of variance and linear regression.Results: The research expresses that while compared with the baseline value of entering, with the anaesthesia deepen the value of BIS becomes gradually lower (P < 0.01), which hint the cerebral pallium being placed in the restraint appearance in depth. The value of BIS is total to first rise and then stepped down with change of aortic cross-clamp, open and the temperature in CPB. When release of aortic clamping, heart recover again and rewarmed to 36 C the value of BIS reached the top. The changes of value of BIS is correlation with changes of nasopharyngeal temperature , rectal temperature, perfusion quantum and perfusion pressure (P< 0.05). The influential factor to the BIS value were one by one in order for nasopharyngeal temperature, rectal temperature > perfusion pressure > perfusion quantum (P< 0.01). Though the MAP, CVP is not related with the BIS, the MAP changes with BIS to have the related trend in clinic. Blood gas analysis showed PO22, PCO2, pH stability during CPB.In a word, before CPB the value of BIS is primarily affected by anaesthetize depth, deepen with the anaesthesia depth namely and lower, and during the period of CPB under the situation of doing not annex to anaesthetize the medicine, the value of the BIS is effected on perfusion quantum, perfusion pressure and temperature, the most on temperature.Conclusion: The BIS is in addition to accurately reflecting the depth of anaesthetic, during CPB various factors also effects the BIS to a large extent. We concluded that many factors in CPB, especially perfusion quantum, perfusion pressure, nasopharyngeal temperature, rectal temperature, also effect brain function and conscious level, of patients...