MAGNESIUM-SULFATE ENHANCES RESIDUAL NEUROMUSCULAR BLOCK INDUCED BY VECURONIUM

Magnesium sulphate (MgSO4) is currently used for haemodynamic control during anaesthesia and the early postoperative period. We have investi gated the effect of this treatment on residual neuromuscular block aft er administration of vecuronium. Twenty adult patients were allocated randomly to one of two groups to receive MgSO4 60 mg kg(-1) either at recovery from vecuronium block to a train-of-four (TOF) ratio of 0.7, or 1 h after recovery to a TOF ratio of 0.7. Neuromuscular transmissio n was monitored using electromyography and TOF stimulation. MgSO4 caus ed rapid and profound recurarization in all 20 patients. MgSO4 decreas ed the amount of acetylcholine released at the motor nerve terminal an d thus may lead to recurarization in patients previously exposed to ne uromuscular blocking agents.