Abstracts of Posters Presented at the International Anesthesia Research Society; 72nd Clinical and Scientific Congress; Orlando, FL; March 7-11, 1998: Ambulatory Anesthesia
The ultrashort-acting opioid agonist remifentanil has the potential for use in monitored anesthetic care and in outpatient procedures. To determine the drug's recovery profile, we examined its effects on mood and psychomotor and cognitive performance in healthy volunteers. As a measure of physiological effects, we also assessed pupil constriction (miosis).
Methods: With approval from the IRB, healthy volunteers (n=7), whose ages ranged from 21 to 39 yr (mean age 25 yr) were enrolled in a prospective, randomized, double-blind, placebo-controlled, crossover trial. In a semi-recumbent position, subjects received an infusion of saline or remifentanil over 120 min in an upper-extremity vein. The age- and weight-adjusted infusion (determined with Stanpump, a computer modeling software package) provided three constant plasma levels for 40 min each: 0.75, 1.5, and 3.0 ng/ml. Mood forms and psychomotor tests were completed and miosis was assessed before, during, and after the infusions.
Results: Dose-related effects were observed by increases in visual analog scale ratings of sleepy, coasting, high, dizzy, and heavy. After drug infusion was discontinued, recovery as measured by mood indices was rapid (Figure 1). Miosis was dose-related, but recovery from miosis also was rapid. Psychomotor impairment, however, continued for up to 30 min (by Tukey post hoc testing, P<0.05) after the infusion was terminated.
Conclusion: Remifentanil produced the typical subjective effects of an opioid, but recovery was rapid as measured by mood and miosis. Rate of recovery as measured by psychomotor performance was slower. This study shows the need for multiple measures of behavior and physiology to assess the time course of recovery from agents used for conscious sedation.
Supported in part by NIDA grant DA-08573.