ANTICHOLINERGIC PREMEDICATION INFLUENCES THE INCIDENCE OF POSTOPERATIVE SHIVERING

We studied 225 healthy adult patients undergoing ENT, dental or orthop aedic surgery, they were allocated randomly to receive one of three di fferent premedications, all given i.m. 1 h before operation. Group 1 r eceived morphine 0.15 mg kg(-1) and metoclopramide 10 mg; group 2 rece ived morphine 0.15 mg kg(-1) and glycopyrronium 5 mu g kg(-1); group 3 received morphine 0.15 mg kg(-1) and hyoscine 5 mu g kg(-1). Patients who were premedicated with an anticholinergic had a significantly gre ater incidence and severity of postoperative shivering than those in t he metoclopramide group. There was no difference in core temperature b etween patients who shivered and those who did not, either before or d uring the shivering episode. Shivering did not cause any clinically si gnificant changes in heart rate, arterial pressure, ventilatory freque ncy or oxygen saturation. As this effect occurred with both glycopyrro nium and hyoscine, it suggests that the mechanism by which postoperati ve shivering is influenced is peripheral to the central nervous system .