The analgesic effects of subhypnotic doses of propofol in human volunteers with experimentally induced tourniquet pain.

This double-blind, placebo-controlled study was performed to determine whether subhypnotic doses of propofol have analgesic or sedative effects. Of 48 subjects randomly assigned to 1 of 4 bolus-infusion treatment groups, group 1 (n = 16) received propofol at 16 micrograms/kg per minute; group 2 (n = 16) received propofol at 32 micrograms/kg per minute; and group 3 (n = 8) received 10% intralipids at 16 micrograms/kg per minute; and group 4 (n = 8) received 20% intralipids at 32 micrograms/kg per minute. Following a bolus of the study drug, a maintenance infusion was started and continued throughout the study. Thirty minutes after the study drug began infusing, an Observer's Assessment of Alertness/Sedation Scale was completed, a tourniquet was inflated, and a maximum tourniquet tolerance time (TTT) was obtained. Pain was assessed every 5 minutes while the tourniquet was inflated and immediately before deflation using a 0 to 10 verbally administered numeric rating scale (NRS). No significant differences in TTT were noted between the 2 propofol groups. However, the TTT for both propofol groups differed significantly from the control group (intralipid groups combined) (P < .05). There was a statistically significant difference in the time it took the propofol groups to reach a NRS score of 8 or greater when compared with the control group (P < .05). Sedation scores differed significantly between the control and the propofol at 32 micrograms/kg per minute groups (P < .05). The results of this study suggest that propofol given at subhypnotic doses could serve as a valuable adjunct for acute postoperative pain management.