Effect of pre-emptive hydromorphone administration on postoperative pain relief - a randomized controlled trial

Background and aim of study: Pre-emptive analgesia represents a treatment s trategy which tries to prevent the development of pain by inhibiting centra l reactions to peripheral sensory stimuli. In a prospective randomised doub le-blind placebo-controlled study, the effect of oral premedication with 4 mg of a slow-release hydromorphone preparation on postoperative piritramide consumption and subjective pain perception is being evaluated. Patients and methods: 96 women undergoing hysterectomy were randomly assign ed to four study groups. Patients from groups 1 and 2 received hydromorphon e and placebo respectively two hours before surgery, while those from group s 3 and 4 were given the same substances one hour after the end of the oper ation. Postoperative pain relief was provided by a patient-controlled infus ion pump with piritramide. The intensity of postoperative pain as perceived by the patients was quantified on a visual analogue scale. Piritramide con sumption and pain scores were recorded at 1 and 24 hours after surgery. App roval of the local Ethics Committee had been obtained beforehand as well as written informed consent from the patients. Results: No significant differences in piritramide consumption were observe d in between the four study groups. Visual analogue scale (VAS) ratings at 1 and 24 hours after surgery did not show any significant differences eithe r - irrespective of whether the patients had received hydromorphone or plac ebo preoperatively or postoperatively. Conclusion: In our study, oral administration of 4 mg of slow-release hydro morphone did not show any greater pre-emptive analgesic effect than placebo .