INTRAVENOUS VERSUS EPIDURAL MAGNESIUM ADJUNCT ON POSTOPERATIVE PAIN IN PATIENTS RECEIVING GENERAL ANAESTHESIA FOR ABDOMINAL SURGERY

Abstract

Background: Although, magnesium is a potent postoperative analgesic adjunct, its most effective route of administration is undetermined.

Patients and Methods: Fifty-two patients, aged 18 – 65years, with American Society of Anesthesiologist (ASA) I and II, were randomised into three groups. Group Areceived IV 50 mg/kg magnesium and placebo epidural; group B (Epidural) received IV placebo and 250mg magnesium epidural, while group C (Control) received both IVand epidural placebo. The postoperative analgesic profile was recorded.

Results: Socio-demographic indices were comparable. The time to first request for rescue analgesics was statistically longer in epidural magnesium, 660±20 mins, versus IV, 540±30 mins, while both were longer than placebo, 380±20 mins, (p-value 0.02). The mean rescue doses were statistically lower in epidural magnesium, 1 (5%) versus IVmagnesium, 2 (13%) and placebo, 3 (17%), p-value 0.001. The mean total 24-hours rescue morphine consumed were lower with epidural magnesium, 1.12±1.04mg, versus IV, 1.18±0.82mg and in turn, versus lower than placebo, 3.02±0.84mg, p-value 0.04.

Conclusion: Epidural magnesium is better than IV, in extending postoperative analgesia duration, and reducing both rescue doses and the total 24-hours rescue opioid consumed.