Peri‐operative intravenous administration of magnesium sulphate and postoperative pain: a meta‐analysis

Intravenous magnesium has been reported to improve postoperative pain; however, the evidence is inconsistent. The objective of this quantitative systematic review is to evaluate whether or not the peri‐operative administration of intravenous magnesium can reduce postoperative pain. Twenty‐five trials comparing magnesium with placebo were identified. Independent of the mode of administration (bolus or continuous infusion), peri‐operative magnesium reduced cumulative intravenous morphine consumption by 24.4% (mean difference: 7.6 mg, 95% CI −9.5 to −5.8 mg; p < 0.00001) at 24 h postoperatively. Numeric pain scores at rest and on movement at 24 h postoperatively were reduced by 4.2 (95% CI −6.3 to −2.1; p < 0.0001) and 9.2 (95% CI −16.1 to −2.3; p = 0.009) out of 100, respectively. We conclude that peri‐operative intravenous magnesium reduces opioid consumption, and to a lesser extent, pain scores, in the first 24 h postoperatively, without any reported serious adverse effects.