Effects Of Different P_ETCO₂ On Bispectral In Patient Undergoing General Anesthesia Combind Epidural Block Anesthesia

Objective: The aim of this study was to investigate the changes in bispectral index values in different P_ETCO₂level.Methods: Thirty ASA I～II patients who underwent operation on abdominal region were included in the study. Patients were premedicated with atropine(0.5mg) and luminal(0.1)and were to receive general anesthesia in combination with epidural block anesthesia. Intraoperative patients were randomized to change P_ETCO₂ in this order: 35,25,35,45,35mmHg or 35,45,35,25,35mmHg (1mmHg= 0.133kpa). After each adjustment, stabilized 20 minutes. Bispectral index values were recorded in each level. And at the same time other monitoring index ,such as blood pressure (BP),heart rate (HR), saturation of Pulse Oxygen (SPO₂)were recorded.Results: Bispectral index values of P_ETCO₂ 25mmHg level was greater than P_ETCO₂ 35mmHg level, and the differences was significant (p<0.01) .compared with P_ETCO₂ 45mmHg, the bispectral index values of 25mmHg level was larger , and the differences was significant (p<0.01) . Bispectral index value was inversely related to the P_ETCO₂ in certain numerical range.Conclusion: Intraoperative change P_ETCO₂ will influence bispectral index value. P_ETCO₂ was inversely related to bispectral index. With the decrease of P_ETCO₂ , the value of bispectral index will increase. Anaesthetist should pay attention.