Effect of transcutaneous electrical acupoint stimulation on sedative efficacy during induction of anesthesia with propofol

Abstract

Objective To evaluate the effect of transcutaneous electrical acupoint stimulation (TEAS) on sedative efficacy during induction of anesthesia with propofol.Methods Patients,of ASA physical status Ⅰ or Ⅱ,aged 21-69 yr,scheduled for elective thyroid surgery,were randomly divided into 2 groups using a random number table:control group (group C) and TEAS group.TEAS was applied to bilateral Hegu and Neiguan acupoints for 30 min.The frequency was 2/100 Hz,wave length was 0.2-0.6 ms and the intensity was maintained at about 8-12 mA according to the current that could be tolerated.Induction of anesthesia was started at the end of TEAS.Sequential method was used to determine the median effective target plasma concentration (EC50) of propofol causing loss of consciousness in each group.The initial target plasma concentration of propofol was 3 μg/ml.BIS value was recorded every 30 s within 5-8 min after loss of consciousness and the average BIS value was calculated.It was considered to be positive response when the average BIS value was below 50.The target concentration of propofol was decreased/increased by 0.3 μg/ml in the next patient.Results EC50 of propofol causing loss of consciousness was 3.08 μg/ml in group TEAS,and 3.70 μg/ml in group C,and there was significant difference between the two groups.Conclusion TEAS can enhance the sedative efficacy during induction of anesthesia with propofol in the patients. Key words: Electric stimulation therapy; Propofol; Conscious sedation