Abstract
Aim: To assess the efficiency of pre-emptive analgesia in a clinical setting as opposed to closely controlled animal models, looking at postoperative pain scores, total analgesia requirement and amount of general anaesthetic agent required during surgery.
Methods and Results. Subject to exclusions, 40 patients undergoing day-case arthroscopy of the knee (mean age 44 years, ASA grade 1–2) were randomized into two treatment groups. All patients had general anaesthesia. The trial group received an injection of 15mI 0.5% Bupivicaine / 1/200,000 adrenaline pre-emptively. After surgery a placebo injection was given of 15ml normal saline in an identical manner. The control group received the opposite order. Additional post-operative analgesia, if required, was administered in recovery. This was recorded, also total dose of propofol used, time to awakening, visual analogue pain score at 15 / 30 / 60 minutes, postoperative nausea and vomiting at 30 minutes and the number of delayed discharges. Although no difference was observed in postoperative pain scores at 15, 30 or 60 minutes, a trend for the trial group to require less analgesia in recovery was observed (Chi squared =9.74, p=0. 1) but this was not statistically significant.
There was no difference in mean dose of propofol used in either group, 15mg/kg/hr (sd=2.85) trial versus 14.6mg/kg/hr (sd=1.96) control.
Conclusion: Local anaesthetic given pre-emptively appears to be no more effective at controlling pain in the immediate postoperative period than the current standard practice of postoperative injection. It’s effect in clinical practice may be less dramatic than that observed in more controlled animal models and a larger study may be required to show a statistically significant difference.
The abstracts were prepared by Mr R. B. Smith. Correspondence should be addressed to him at the British Orthopaedic Association, Royal College of Surgeons, 35-43 Lincoln’s Inn Fields, London WC2A 3PN.
