[Use of remifentanil in ambulatory obstetric-gynecologic surgery. A dose-effect study]

Remifentanil, a recently commercialised opioid, is characterised by a predictable and non cumulative effect which vanishes rapidly without determining side effects in the long term. These characteristics make remifentanil an ideal opioid in continuous infusion for the ambulatory surgery setting. Aim of this study was to assess the ideal dose of remifentanil, administered in bolus before propofol, in patients undergoing uterine curettage and assisted by mask ventilation in 100% oxygen.

Sixty patients, ASA status I-II, scheduled for uterine curettage, were divided into three study groups according to the bolus dose of remifentanil received before the induction agent: group A (n = 20) 1 microgram/kg; group B (n = 20) 2 micrograms/kg; group C (n = 20) 2 micrograms/kg. All patients were assisted by 100% oxygen ventilation with facial mask. During surgery the following were recorded: time to spontaneous ventilation (in case of post induction apnea); incidence of somatic and autonomic responses to surgical stress (treated with remifentanil in bolus). At the end of surgery the times to response to simple verbal commands, to discharge from the recovery room (by Aldrete score every 5') and to discharge from hospital (by PADSS score every 30') were registered.

All patients presented post-induction apnea with a significantly more rapid return to spontaneous ventilation in group A. Six patients of group A responded to surgical stress while in groups B and C there was no need for supplementary boluses (p < 0.05). Five patients of group C were treated with atropine for bradycardia, in four of group C it was necessary to administer succinylcholine for thoracic rigidity. No significant differences regarding the anesthesia recovery times were observed. All patients were discharged from the recovery room after 10' from the end of surgery. Overall, the qualification for discharge from hospital was obtained at the second PADSS score control, except for one group A patient who incurred in metrorrhagia.

The administration in bolus of remifentanil, before the inducing agent, permits short-term surgery in ambulatory surgery settings thanks to the rapid recovery of vital functions. Compared to the other doses, the 1.5 micrograms/kg dose guaranteed a good control over surgical stress without influencing the speed of awakening and without determining uncomfortable side effects.