Clonidine at induction reduces shivering after general anaesthesia

Purpose: Postanaesthetic shivering occurs in 5-65% of patients. In addition to causing discomfort, it is associated with deleterious consequences. Our objective was to investigate the effect of 1.50 mu g donidine, at induction of anaesthesia, on perioperative core and peripheral temperature, incidence of postanaesthetic:shivering and patients' perception of cold. Methods: Sixty ASA I or 2 patients scheduled for elective orthopaedic limb surgery were randomly allocated to group 1, who received 150 mu g clonidine iv, or group 2, who received a saline bolus iv, before induction. In all patients, anaesthesia was induced with fentanyl and propofol and maintained by spontaneous:respiration (via a laryngeal mask airway) of oxygen, nitrous oxide and enflurane. Core (nasopharyngeal) and peripheral (dorsal hand) temperatures were recorded at induction and 15-min intervals. Nurses, unaware of the treatment groups, recorded visible shivering in the recovery room. When cognitive function returned, patients were asked to grade; their perception of cold on a 10 cm linear analogue scale, higher scores indicating heat discomfort. Results: While core temperature decreased and peripheral temperature increased:in both groups;there was no difference between the groups at any time. However, there was a lower incidence of shivering in the clonidine group (20% vs 66.7%, P<0.001). Patients receiving donidine felt warmer; thermal comfort score (median interquartile range) 5.9 (5.0-7.2) vs 5.0 (4.5-6.0), P<0.05). Conclusion: Clonidine 150 g iv at induction of anaesthesia: reduces the incidence of shivering and patients' subjective perception of cold on emergence from general anaesthesia.