The Effect of Magnesium Sulfate Infusion on Postoperative Opioid Consumption in Abdominal Hysterectomy: A Randomised, Double-Blind Trial.

Abstract

Objective: To assess the impact of magnesium sulfate infusion on total opioid consumption following abdominal hysterectomy in a clinical setting.

Study design: Controlled, randomised, prospective, and double-blind trial. Place and Duration of the Study: Department of Gynaecology, Giresun Gynaecology and Children's Diseases Training and Research Hospital, Giresun, Turkiye, from November 2023 to April 2024.

Methodology: A total of 48 participants were randomly assigned to two groups: Group M (magnesium sulfate infusion) and Group N (placebo). Participants in Group M were administered a bolus 20 mg/kg MgSO4 in 100 mL of saline over 15 minutes prior to induction, followed by 20 mg/kg/h until skin closure. Participants in Group N received an equivalent volume of saline. The primary outcome was total opioid consumption within the first 24 hours, while secondary outcomes included pain scores, remifentanil use, haemodynamic parameters, and adverse effects.

Results: Postoperative opioid consumption during the first 24 hours was significantly lower in Group M (35.6 ± 15.2 mg) compared to Group N (44.9 ± 14.1 mg), with a p-value of 0.032. Pain scores were also significantly lower in Group M at 24 hours (p = 0.008) at rest, at 4 hours (p = 0.022), and 6 hours (p = 0.041) during movement. No significant differences were observed in remifentanil consumption, haemodynamic parameters, sedation levels, or nausea between the two groups.

Conclusion: The intraoperative administration of magnesium sulphate significantly reduced opioid consumption and pain scores following abdominal hysterectomy. These findings support its use within multimodal analgesia strategies.

Key words: Analgesia, Gynaecologic Anaesthesia, Hysterectomy, Magnesium sulfate, Patient-controlled analgesia, Postoperative pain.