Effects of electroacupuncture on minimum alveolar concentration of isoflurane in anesthetized horses during MRI examination

. Introduction Isoflurane causes dose-dependent cardiovascular adverse effects. Because of the high anesthetic mortality in horses and the risk of onset of postanesthetic myopathy, the reduction of isoflurane requirements appears to be indispensable in minimizing its dose-dependent side effects. Since it was found that the minimum alveolar concentration (MAC) of isoflurane was reduced by electroacupuncture (EA) in dogs, in this study the effects of electroacupuncture on MAC in horses under isoflurane general anesthesia were evaluated. Other descriptive-subjective parameters such as quality of recovery, depth, and stability of anesthetic plane were evaluated. 2. Materials and Methods Fifteen lame adult horses underwent general anesthesia for MRI examination and were randomly assigned into 2 groups. In the first group, 10 horses were treated with EA at acupoints GV1, Bai Hui, GV6, GV8, GV11, GV12, ST36, LI4, and PC6 for 30 minutes at 20 Hz. In the second group, 5 horses were used as control group, without EA. 3. Results EA lowered the MAC of isoflurane by 31.3%: the mean ! SD isoflurane MAC for the EA group was 0.9% ! 0.2%, versus 1.3% ! 0.1% for the control group. There was no significant difference regarding rectal temperature, heart rate, systolic and diastolic arterial pressures, and quality of recovery. Depth and stability of anesthetic plane were significantly shallower in the control group (p " 0.002). 4. Discussion EA decreases the isoflurane requirement in horses undergoing general anesthesia. In conclusion, EA could be considered a valid tool as part of a multimodal anesthetic approach.