Effects Of Midazolam With Different Dosage On Sedation With Propofol During Spinal Anesthesia

Objective: To assess the effects of midazolam with different dosage on the propofol requirements and incidence of complications during sedation under spinal anesthesia. Methods: 100 patients(18-50yr of age, ASA physical status I or II)undergoing elective lower extremity operation were randomly divided into midazolam1(M1), midazolam2(M2), midazolam3(M3), midazolam4(M4) and control(C) groups. After spinal anesthesia was instituted, patients in the Ml, M2, M3, M4 and C group received 0.02mg ·kg^-1, 0.03mg ·kg^-1, 0.04mg ·kg^-1, 0.05mg ·kg^-1 midazolam and 1.5ml saline iv respectively. We provided sedation using continuous infusion of propofol. Infusion rates were adjusted to maintain an appropriate level of sedation using bispectral index(BIS)(60-80) and the Observer's Assessment of Alertness/Sedation(OAA/S) scale (range 2-3). The sedative infusion was discontinued at the end of surgery. During sedation, the propofol requirements and complications were recorded, blood gas analysis is made and patients were asked, the next day, whether they remembered intraoperative events. Result: The requirements of propofol in midazolam group were lower than control group(P < 0.05). In midazolam2, midazolam3 and midazolam4 groups, the incidence of restlessness and intraoperative memory were lower than control group(P < 0.05), but have no difference on other complications(P> 0.05). In midazolam4 and control groups, pH and PCO2 were lower than other groups. Conclusions: Midazolam reduced requirements and complications of propofol and enhance amnesia during sedation for spinal anesthesia. The optimal dosage of midazolam administered is 0.03mg ·kg^-1.