Purpose: The study goal was to assess the efficacy of pre-emptive analgesia in a clinical setting.
Type of study: A block randomized, double-blind design was used.
Methods: Subjects were 40 patients undergoing day-case arthroscopy of the knee. The trial group received a prophylactic injection of bupivacaine with adrenaline. After surgery, a placebo injection was given. The postsurgical injection group received identical injections in reverse order. There was no difference in the mean dose of propofol used to maintain general anesthesia between groups: 15 mg/kg/h (standard deviation [SD] = 2.85) trial versus 14.6 mg/kg/h (SD = 1.96) postsurgical injection (95% confidence interval [CI] = -1.14 to 1.94).
Results: Although no statistically significant difference was observed in postoperative pain scores at 15, 30, or 60 minutes, there was a trend for the trial group to require less analgesia in recovery (chi2 = 9.74; P =.1).
Conclusions: Prophylactic local anesthesia confers no statistically significant reduction in pain scores or perioperative general anesthetic requirements as compared with postoperative administration. The pre-emptive effect in clinical practice may be less dramatic than that observed in more controlled animal models. Further studies are required to investigate the magnitude of the pre-emptive effect in clinical practice.