A comparison of two different doses of morphine added to spinal bupivacaine for inguinal hernia repair.

Background And Objectives: The aim of this study was to compare the effects of two different doses of intrathecal morphine on postoperative analgesia, postoperative first mobilization and urination times and the severity of side effects.

Methods: After Institutional Ethical Committee approval, 48 ASA I-II patients were enrolled in this randomized double-blinded study. Spinal anesthesia was performed with 0.1mg (Group I, n=22) or 0.4mg (Group II, n=26) ITM in addition to 7.5mg heavy bupivacaine. The first analgesic requirement, first mobilization and voiding times, and postoperative side effects were recorded. Statistical analyses were performed using SPSS 15.0 and p<0.05 was considered as statistically significant. The numeric data were analyzed by the t-test and presented as mean±SD. Categorical data were analyzed with the chi-square test and expressed as number of patients and percentage.

Results: Demographic data were similar among groups. There were no differences related to postoperative pain, first analgesic requirements, and first mobilization and first voiding times. The only difference between two groups was the vomiting incidence. In Group II 23% (n=6) of the patients had vomiting during the first postoperative 24h compared to 0% in Group I (p=0.025).

Conclusion: For inguinal hernia repairs, the dose of 0.1mg of ITM provides comparable postoperative analgesia with a dose of 0.4mg, with significantly lower vomiting incidence when combined with low dose heavy bupivacaine.