Remifentanil versus alfentanil in a balanced anesthetic technique for total abdominal hysterectomy

Study Objectives: To compare the intraoperative effects and recovery characteristics of remifentanil hydrochloride and alfentanil when administered as part of balanced anesthesia, and to assess the of an additional when administered as part of balanced analgesic pretreatment before removal of the uterus. Design: Multicentre, double-blind, randomized, parallel-group study. Setting: Two university hospitals. Patients: 35 ASA physical status I, II, and III women scheduled for elective total abdominal hysterectomy with general endotracheal anesthesia. Interventions: Patients were premedicated with midazolam 0.05 mg/kg intravenously (IV). Anesthesia was induced with thiopental 2 mg/kg, vecuronium 0.15 mg/kg, and a single dose of opioid over 60 seconds (Pump 1): remifentanil 2 mu g/kg, and a Remi/Remi groups) or alfentanil 50 mu g/kg (Alf/Placebo group). Anesthesia was maintained with a nitrous oxide/oxygen mixture (66:34 ratio) and a continous opioid infusion: remifentanil 0.25 mu g/kg/min (Remi/Placebo and Remi/Remi) or alfentanil 0.5 mu g/kg/min (Alf/Placebo). Intraoperative responses were controlled with single doses initiated (Pump 2): remifentanil 0.25 mu g/kg/min (Remi/Remi) or saline doses (Remi/Placebo and Alf/Placebo). Intraoperative responses were controlled with single doses of opioid and/or rate titrations via Pump 1. Pump 2 was terminated on removal of the uterus. Pump 1 was terminated at skin closure. Measurements and Main Results: The mean (+/-SD) opioid infusion rates administered for the duration of Pump 2 to suppress responses to removal of the uterus were 0.49 +/- 0.27 mu g/kg/min, 1.99 +/- 1.34 mu g/kg/min, and 0.49 +/- 0.07 mu g/kg/min for the Remi/Placebo, Alf/Placebo, and Remi/Remi groups, respectively. At these rates, similar proportions of patients in the Remi/Placebo (67%) and the Alf/Placebo (60%) groups had responses. Fewer patients had responses in the Remi/Remi group (8%) compared with the Remi/Placebo and Alf/Placebo groups (p < 0.05). The mean total opioid doses used during maintenance were 84.6 mu g/kg (Remi/Placebo), 393 mu g/kg (Alf/Placebo), and 68.7 mu g/kg (Remi/Remi). Awakening times were significantly shorter (p < 0.05) in the remifentanil population compared with the alfentanil population, but discharge times were similar. More patients recieved naloxone to reverse opioid effects in the alfentanil population (60%) than in the remifentanil population (20%) (p < 0.05). Conclusions: A mean remifentanil infusion of 0.49 mu g/kg/min is as effective as a mean alfentanil infusion of 1.99 mu g/kg/min in suppressing intraoperative reponses. Doubling of the remifentanil infusion to 0.5 mu g/kg/min before the major stress event improves suppression of responses and lowers intraoperative use of remifentanil without prolonging recovery times. Remifentanil allows faster awakening times than alfentanil, but preemptive administration of postoperative analgesics is recommended to facilitate discharge. (C) 1997 by Elsevier Science Inc.