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 remifentanil 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 dose ratio of 1:7 (remifentanil:alfentanil). Methods. Seventy-nine ASA I-III patients scheduled for elective ophthalmologic surgery participated in this multicenter, double-blind study. Patients were randomized into three groups: remifentanil (remifentanil 1 μg/kg and placebo infusion); remifentanil infusion (remifentanil 1 μg/kg and infusion of 0.2 μg/kg/min); and alfentanil (alfentanil 7 μg/kg and placebo infusion). Supplemental doses of the respective opioid were given as needed. Results. Seventy-seven percent of patients in the remifentanil group were pain-free at the time of the block placement compared with 44% in the alfentanil group (P < .05). Eighty percent of patients in the remifentanil infusion group were pain-free. Although the occurrence of respiratory depression (14%) was higher in the remifentanil infusion group, it was short-lived (≤5 minutes) and resolved spontaneously. More than 89% of patients were awake and alert prior to surgery, and ≥85% bypassed the phase I recovery area. Nausea and vomiting were rare. Conclusions. Remifentanil 1 μg/kg results in superior analgesia compared with alfentanil 7 μg/kg when used during the placement of ophthalmologic nerve blocks. The combination of a single dose of remifentanil followed by a continuous infusion was equally effective but resulted in a higher incidence of respiratory depression.