Comparison of fentanyl versus fentanyl plus magnesium as post-operative epidural analgesia in orthopedic hip surgeries

Introduction: Post-operative pain is often inadequately treated. Optimal utilization of the available resources is essential for improving pain management. Magnesium has antinociceptive effects in animal and human models of pain. Materials and methods: 60 patients of either sex, belonging to 45-60 years of age, ASA grade I and II admitted for orthopedic hip surgeries. In the post-operative period when patient first complained of pain, they received either 50 mcg of Fentanyl (GROUP-F) or 50 mcg of Fentanyl plus 50 mg of Magnesium (GROUP-FM) diluted to 6 ml with normal saline. The parameters monitored were duration of analgesia, quality of analgesia (vas and vrs), cardio-respiratory effects: pulse rate, blood pressure (sbp and dbp), and respiratory rate and side effects like: nausea, vomiting, hypotension, sedation, respiratory depression. Results: Mean onset of analgesia in Group F was 16.2 ± 2.67 min and in Group FM was 15.9± 3.4 min. The duration of analgesia in Group F was 160± 18.19 min and in Group FM was 337.3 ± 47.48 min. In our study, there is mild fall in pulse rate and diastolic BP with both groups, more so with Fentanyl plus Magnesium group, and respiratory parameters were stable in both groups. In our study 50 mg of epidural Magnesium coadministered with Fentanyl in Group FM resulted in lower VAS scores at 2,3,4 hours postoperatively. Conclusion: Epidural Magnesium (50 mg) as an adjuvant to epidural Fentanyl (50 mcg) for postoperative analgesia resulted in prolonged duration of analgesia when compared to epidural Fentanyl (50 mcg) alone.