What is the optimal dose of intrathecal meperidine in open prostate surgery? A prospective double-blind randomized study

Objectives: This study was an analysis of the effect of different dosages of intrathecal meperidine (40 mg, 50 mg, 60 mg, and 70 mg) on hemodynamic parameters, the duration of neural blockade, and the incidence of meperidine-related side effects in patients who underwent an open prostatectomy. Methods: Sixty patients who underwent an open prostatectomy with combined spinal-epidural anesthesia were included. The patients were allocated to receive 1 of 4 different dosages of intrathecal meperidine (n=15 for each group): Group I: 40 mg, Group II: 50 mg, Group III: 60 mg, and Group IV: 70 mg. The duration of the block procedure, surgery duration, highest sensory block level, and anesthetic complications were recorded and analyzed. Results: At 20 minutes after the spinal injection, the maximum sensory block level was T6 in Group I and II, and it was T5 in Group III and IV. The mean motor block scores at 20 minutes after the spinal injection were lower in Group I compared with the other groups (p<0.001 for all). The motor block duration was significantly shorter in Group I and II than in Group III and IV (p<0.001 for all). Surgeon satisfaction was greater in Group II, III, and IV compared with Group I (p<0.001 for all). Patient satisfaction was better in Group III and IV compared with Groups I and II (p<0.001 for all). Conclusion: Intrathecal meperidine at a dose of 60 mg exerted a sufficient analgesic effect with minimum side effects in patients undergoing open prostatectomy.