Remifentanil versus alfentanil as analgesic adjuncts during placement of ophthalmologic nerve blocks

Background and Objectives. Short-acting opioids are often used prior to the placement of ophthalmologic nerve blocks. This study examines whether remi fentanil would provide superior analgesia compared with alfentanil, without oversedation or prolonged recovery when given either as a single dose over 30 seconds or as a single dose followed by a continuous infusion, in a dos e ratio of 1:7 (remifentanil:alfentanil). Methods. Seventy-nine ASA I-III p atients scheduled for elective ophthalmologic surgery participated in this multicenter, double-blind study. Patients were randomized into three groups : remifentanil (remifentanil 1 mu g/kg and placebo infusion); remifentanil infusion (remifentanil 1 mu g/kg and infusion of 0.2 mu g/kg/min); and alfe ntanil (alfentanil 7 mu g/kg and placebo infusion). Supplemental doses of t he respective opioid were given as needed. Results. Seventy-seven percent o f patients in the remifentanil group were pain-free at the time of the bloc k placement compared with 44% in the alfentanil group (P < .05). Eighty per cent of patients in the remifentanil infusion group were pain-free, Althoug h the occurrence of respiratory depression (14%) was higher in the :remifen tanil infusion group, it was short-lived (less than or equal to 5 minutes) and resolved spontaneously. More than 89% of patients were awake and alert prior to surgery, and greater than or equal to 85% bypassed the phase I rec overy area. Nausea and vomiting were rare. Conclusions. Remifentanil 1 mu g /kg results in superior analgesia compared with alfentanil 7 mu g/kg when u sed during the placement of ophthalmologic nerve blocks. The combination of a single dose of remifentanil followed by a continuous infusion was equall y effective but resulted in a higher incidence of respiratory depression.