Acupuncture facilitates neuromuscular and oculomotor responses to skin incision with no influence on auditory evoked potentials under sevoflurane anaesthesia.

BACKGROUND

More sevoflurane was recently found to be required to prevent movement in response to surgical incision in anaesthetized patients subjected to electro-acupuncture (EA) than to sham procedures. The present study was designed to compare differences in movement, dilatation of the pupils, divergence of the eye axes and activity of auditory evoked potentials (AEPs) between patients given and those not given EA under standardized sevoflurane anaesthesia.

METHODS

Neuromuscular, oculomotor and AEP responses to skin incision were assessed with and without a bilateral 2-Hz burst EA in patients under steady-state anaesthesia maintained with 1.8% of sevoflurane. Forty-five healthy patients, scheduled for laparoscopic sterilization, were randomized for EA (n = 22) or sham (n = 23) procedures between induction of anaesthesia and start of surgery. Middle latency AEP activity was recorded and interpreted by the A-line ARX (autoregression with exogenous input) index (AAI).

RESULTS

More acupuncture than sham patients were found to respond to skin incision with movement of the neck or limbs (77% vs. 43%; P = 0.021), dilatation of the pupils (77% vs. 39%; P = 0.001) and divergence of the eye axes (72% vs. 39%; P = 0.023), whereas there was no difference in AAI response.

CONCLUSION

Electro-acupuncture facilitates physiological responses to nociceptive stimulation under sevoflurane anaesthesia. Differences in neuromuscular and oculomotor responses between acupuncture and sham patients under general anaesthesia are probably not associated with interaction between EA and the depth of anaesthesia, as AEP activity was similar in the two groups.