Effect of Transcutaneous Electrical Acupoint Stimulation on Half Effective Target Concentration in Patients with Midazolam Induced Disappearance
GUO Yan-hui,ZHAO Chong-fa
Department of anesthesiology, Tianjin Haihe Hospital, Tianjin (300350), China
Abstract:
Objective To determine the effect of transcutaneous electrical acupoint stimulation (TEAS) on half effective target concentration (EC 50 ) in patients with consciousness loss induced by midazolam. Methods Selective spinal anesthesia for orthopedic lower limb surgery patients were randomly divided into two groups: percutaneous acupoint electrical stimulation group (T group) and control group (C group), using implementation of intraspinal anesthesia. The patients in T group were given TEAS, and the stimulation current was adjusted to the maximum intensity that the patient could tolerate. Bilateral Hegu and Neiguan points were selected and midazolam was injected intravenously 20 min later. In group C, the electrodes were attached to the corresponding points, and the stimulator was connected without electrical stimulation. OAA/S score of less than 2 points was judged to be a loss of consciousness. The initial target concentration of midazolam was 80ng/mL and the adjacent dose ratio was 1: 1. 1. If the patient’s consciousness disappeared, the next patient’s midazolam dose was lowered by a dose gradient, whereas the next patient’s midazolam dose was increased by a dose gradient if the consciousness did not disappear. When the 7 Yin Yang crosses occurred, the experiment was terminated. Half effective dose (EC50) and 95% con?dence interval (CI) of midazolam-induced consciousness loss were calculated by sequential formula. Results The EC50 from midazolam to unconsciousness was 78.6 ng/mL in group T (53.1–116.4 ng/mL in 95% CI) and 90.3 ng/mL in group C (61.4–132.7 ng/mL in 95% CI). The difference was statistically signi?cant (P<0.05). Conclusion TEAS can reduce the consciousness loss of midazolam patients in EC50.
