Propofol at conscious sedation doses produces mild analgesia to cold pressor-induced pain in healthy volunteers

Abstract

Study objective: To determine whether subanesthetic doses of propofol have analgesic effects in healthy volunteers. Design: Prospective, double-blind, placebo-controlled, randomized, crossover trial. Setting: Human psychomotor performance laboratory within our anesthesia and critical care department. Subjects: 12, non-drug abusing volunteers, aged 22 to 38 years. Interventions: Five drug conditions were used in which a loading injection was followed by a 20-minute infusion period: placebo [saline (Intralipid)] injection, Intralipid infusion; propofol 0.125 mg/kg injection, propofol 12.5 mcg/kg/min infusion; propofol 0.25 mg/kg injection, propofol 25 mcg/kg/min infusion; propofol 0.5 mg/kg injection, propofol 50 mcg/kg/min infusion; fentanyl 1.4 mcg/kg injection (positive control), Intralipid infusion. Five minutes into the infusion period and 115 minutes after the infusion period was terminated, subjects immersed their forearms in ice-cold water for three minutes while pain assessments were recorded. Measurements and Main Results: Propofol at the two higher doses during part of the first immersion produced a significant reduction ( p < 0.05) in pain intensity and bothersomeness ratings. However, relative to fentanyl, the analgesia was mild. Propofol did not affect any ratings on the 15-item short-form McGill Pain Questionnaire, whereas fentanyl reduced 10 of the ratings. Conclusion: Our laboratory results are consistent with the commonly accepted clinical practice of supplementing propofol with an opioid in conscious sedation procedures to provide a satisfactory level of pain relief.