Aim: Number of studies revealed that epidural bupivacaine-dexamethasone has the same analgesic potency as bupivacaine-fentanyl with opioid sparing and antiemetic effects. Different doses of dexamethasone were used in different studies. This study was designed to evaluate the optimum dose of epidural dexamethasone for post-operative analgesia.
Materials and methods: In this double-blinded randomized controlled study, we evaluated the efficiency and safety of different doses of epidural dexamethasone for post-operative analgesia in 160 patients aged 45-60 years scheduled for total abdominal hysterectomy. Patient were randomly allocated into four groups to receive a total volume of 10 ml epidural plain bupivacaine 0.25% in the control group (Group D0) with either 4 mg dexamethasone in (Group D4) or 6 mg dexamethasone in (Group D6) or 8 mg dexamethasone in (Group D8). Patients then received general anesthesia. Sedation, satisfaction and visual analog pain scores (VAS) at rest and with effort were measured post-operatively. Meperidine was administered when VAS > or = 4. Intra-operative fentanyl dose, post-operative meperidine consumption and the time to first analgesic requirement were recorded by a blinded observer. Blood glucose was measured pre-operatively and at 4 h and 8 h after study drug administration. Wound healing and infection were assessed after 1 week.
Results: Intraoperative fentanyl requirements were comparable among groups. The time to first analgesic requirement was significantly prolonged 5.5 times in D8 Group but only 1.5 times in D6 and D4 Groups more than the analgesic duration in the control Group D0, with a P < 0.01. There was a significant reduction in post-operative meperidine consumption during the first 24 h in the D8 (75%) in comparison with D6 and D4 Groups (50%), respectively, (P < 0.01) and the control Group D0 (0%) (P < 0.01). VAS scores were significantly lower and patient satisfaction score was significantly higher in the D8 and compared with Groups D6 and D4 (P < 0.01) and the control Group D0 (P < 0.01). Post-operative nausea was significantly lower in the D8, D6 and D4 Groups versus the D0 Group (P < 0.05).
Conclusion: Epidural dexamethasone in a dose of 8 mg is probably more effective than lower doses to control moderate to severe post-operative pain. This dose is not associated with increased glucose level or delayed wound healing.
Keywords: Abdominal hysterectomy; bupivacaine; dexamethasone; epidural; pain.