The role of magnesium as an adjuvant during general anaesthesia

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Anaesthesia. 2006 Nov;61(11):1058-63.

The role of magnesium as an adjuvant during general anaesthesia.

Gupta K, Vohra V, Sood J.

Registrar, Department of Anaesthesiology, Pain and Perioperative

Medicine, Sir Ganga Ram Hospital, Old Rajinder Nagar, New Delhi,

India.

Magnesium sulphate is used extensively in the treatment of

eclampsia, and is also used to treat refractory arrhythmias, asthma,

myocardial ischaemia and acute respiratory failure. We studied the

interaction between magnesium sulphate and the anaesthetic agents

propofol, rocuronium bromide and fentanyl citrate. This randomised,

double blind study was conducted in 50 patients.

The magnesium group A (n = 25) received 30 mg.kg(-1) magnesium

sulphate before induction of anaesthesia and 10 mg.kg(-1)

continuously intra-operatively until the end of surgery. Group B (n

= 25) received the same volume of isotonic saline. Propofol,

rocuronium and fentanyl infusions were started and the patients

lungs' were ventilated with 33% oxygen in nitrous oxide. Anaesthetic

depth was maintained at a bispectral index value of between 40 and

60. Muscle relaxation was maintained at a train-of-four count of 1

throughout surgery using neuromuscular monitoring. The fentanyl

infusion was titrated to haemodynamic variables: heart rate and

blood pressure.

We concluded that magnesium sulphate has anaesthetic, analgesic and

muscle relaxation effects and significantly reduces the drug

requirements of propofol, rocuronium and fentanyl during anaesthesia.