Influence of the perioperative administration of magnesium sulfate on the total dose of anesthetics during general anesthesia. A systematic review and meta-analysis.

Background: Magnesium sulfate displays numerous characteristics that make it a useful drug in anesthesiology (N-methyl-d-aspartate receptor antagonist, vasodilator, antiarrhythmic, inhibitor of catecholamine release and of acetylcholine in the terminal motor plate). The perioperative use of this drug as an adjuvant capable of decreasing the required dose of anesthetics, has been proposed.

Objectives: To assess the influence of intravenous magnesium sulfate administration during general anesthesia on the overall dose of required anesthetics.

Design: A systematic review of controlled randomized trials and meta-analysis.

Data Sources: An electronic bibliography search in MEDLINE and in the Cochrane Database of Controlled trials (CENTRAL) up to 2015.

Study Eligibility Criteria, Participants And Interventions: Randomized, double-blind trials relating to general anesthesia in elective surgery using intravenous magnesium sulfate that provide information about the anesthetic requirements in ASA I and II patients.

Results: 20 clinical trials were selected for the qualitative analysis and 19 for the quantitative one. The use of perioperative intravenous magnesium sulfate reduces the requirement of the anesthetic, propofol during induction (-28.52mg; CI 95% -35.22-1.82; p<0.001) and maintenance (-213.56mg; CI 95% -322.93, -104.18; p<0.001) of anesthesia. Additionally, magnesium sulfate reduces the requirement of neuromuscular non-despolarizing blocking agents (-2.99mg; CI 95% -44.47, -1.99; p<0.001) and the intraoperative consumption of fentanile(-53.57 mcg; CI 95% -75.01, -32.12; p<0.001).

Conclusions: We conclude that perioperative magnesium sulfate acts as a coadjuvant drug capable of reducing anesthetic requirements.