SAFETY OF USING REMIFENTANIL FOR MONITORED ANESTHESIA CARE (MAC) IN OLDER PATIENTS UNDERGOING AMBULATORY COLONOSCOPY*

Abstract

S33 INTRODUCTION: Remifentanil is an FDA-approved synthetic opioid whose application in outpatient procedures requiring brief analgesia is being explored. [1] Outpatient colonoscopy in the elderly is particularly challenging given the brief but intense pain associated with this procedure. In view of its ultra-short half-life, remifentanil may be ideal in this setting. This study was designed to determine the safety of using remifentanil and meperidine in outpatients undergoing colonoscopy. METHODS: Following IRB approval and informed consent, eighty-nine patients were randomized in this double-blind study to receive MAC with either remifentanil (RemiMAC) or meperidine for outpatient colonoscopy. One group received a 1 mg/kg (<or=to 65 yrs) or 0.5 mg/kg (>65 yrs) bolus of meperidine with a placebo infusion. Remifentanil was infused for 5 minutes in the other group at 0.05 [micro sign]g/kg/min (<or=to 65 yrs) or 0.025 [micro sign]g/kg/min (> 65 yrs) prior to beginning the procedure. The remifentanil group also received a placebo bolus. Further adjustments in infusions or aliquots were based on patient response. Age, weight, ASA status, duration of colonscopy and total dose of medications were recorded. Measurements included the incidence of hypertension ([up arrow] SBP >20% of baseline), tachycardia (HR >110 / >20% of baseline), hypotension (SBP <or=to 80 mmHg / >20% of baseline), bradycardia (HR <40 / >20% of baseline], nausea, vomiting, and pruritus. Patient and operator satisfaction were surveyed on a 4 point scale (1=poor, 2=satistfactory, 3=good, 4=excellent). Ventilatory drive (minute ventilation [MV]) and time-to-home readiness were used to assess speed of recovery. Data were analyzed using either t-test (t) Fisher's Exact test (FET) or Mann-Whitney U (MWU). P-value of < 0.05 was considered significant. RESULTS: The two groups were similar with regards to demographics and patient/operator satisfaction. Demographic, side effects, and recovery data are shown in Table 1. Data are expressed as mean +/- SD.Table 1DISCUSSION: This study demonstrates that remifentanil can be safely administered to older patients undergoing colonoscopy as part of a MAC with fewer side effects than meperidine. Although patient and operator satisfaction did not differ, patients receiving RemiMAC had faster recovery of respiratory effort and home readiness than patients receiving an optimally titrated meperidine MAC. Future studies are needed to establish the most efficacious dosing for RemiMAC and compare it to meperidine as used by non-anesthesia providers. This study was supported, in part, by a grant from Glaxo Wellcome Inc.