A COMPARISON OF REMIFENTANIL AND ALFENTANIL IN PATIENTS UNDERGOING MAJOR ABDOMINAL-SURGERY

The efficacy and safety of remifentanil and alfentanil for patients un dergoing major abdominal surgery were compared. Premedicated patients received a loading dose of remifentanil (1.0 mu g.kg(-1); n = 116) and a continuous infusion of 0.5 mu g.kg(-1).min(-1), or a loading dose o f alfentanil (25 mu g.kg(-1); n = 118) and a continuous infusion of 1. 0 mu g.kg(-1).min(-1). Propofol was administered (10 mg every 10 s) un til loss of consciousness. Patients' lungs were ventilated with 66% ni trous oxide and 0.5% (end-tidal) isoflurane in oxygen. The study drug infusion rate was reduced by 50% 5 min after intubation. Alfentanil wa s discontinued 15 min before the end of surgery, whereas remifentanil was continued in the immediate postoperative period at a reduced dose. Responses to intubation (28%) and skin incision (17%) occurred approx imately twice as often in the alfentanil group (15% and 8%; p = 0.014 and p = 0.037, respectively). More patients receiving alfentanil had o ne or more responses to surgery (72% vs. 57%; p = 0.016). The time to spontaneous respiration, adequate respiration, response to verbal comm and and time to recovery room discharge were similar. However, owing t o decreased variability, the time to extubation was shorter with remif entanil than with alfentanil (p = 0.048). There was a similar overall incidence of. adverse events in both groups, 82% and 75% of patients, respectively. Adverse events associated with remifentanil were rapidly controlled by dose reductions. The incidence of intra-operative hypot ension and bradycardia was higher in the remifentanil group (p less th an or equal to 0.033). An initial remifentanil infusion rate of 0.1 mu g.kg(-1).min(-1) titrated to individual need provided postoperative p ain relief in the presence of adequate respiration in 71% of patients. When using remifentanil in the immediate postoperative setting, rapid administration of bolus doses and infusion rate increases resulted in a relatively high incidence of muscle rigidity, respiratory depressio n and apnoea. Changing the postoperative regimen to avoid rapid change s in remifentanil blood concentration resulted in more effective analg esia and dramatically reduced the incidence of adverse events during t his period. In patients undergoing major abdominal surgery, remifentan il appears to offer superior intra-operative haemodynamic stability du ring stressful surgical events compared with alfentanil without compro mising recovery from anaesthesia. Remifentanil can be administered as a postoperative analgesic agent at a starting dose of 0.1 mu g.kg(-1). min(-1); however, it should only be used in the presence of adequate s upervision and monitoring of the patient. Administration of bolus dose s is not recommended in this setting.