EFFECTS OF MAGNESIUM-SULFATE ON SUXAMETHONIUM-INDUCED COMPLICATIONS DURING RAPID-SEQUENCE INDUCTION OF ANESTHESIA

Twenty patients were studied in a double-blind manner to investigate w hether magnesium sulphate, when given during a rapid-sequence inductio n of anaesthesia, lessens the side effects caused by suxamethonium. Pa tients were randomly allocated to two groups; equal volumes of either magnesium sulphate (40 mg.kg(-1)) or saline were given during rapid-se quence induction of anaesthesia, after. thiopentone but before the adm inistration of suxamethonium (1.5 mg.kg(-1)). The changes in the serum potassium concentration, the degree of muscle fasciculations and the presence of postoperative myalgia were recorded. The mean serum potass ium concentration increased by 0.08 mmol.l(-1) in the magnesium group and by 0.1 mmol.l(-1) in the control group at 2 min after injection of suxamethonium; in neither group was there a significant increase from baseline values. The systolic blood pressure and heart rate increased in both groups after tracheal intubation. The incidence of fasciculat ions was significantly lower in the magnesium group. Magnesium did not clinically prolong muscle relaxation. There was no difference between the groups in the incidence of myalgia after surgery (one patient in each group). Since no significant increase in the serum potassium conc entration was demonstrated, no assessment could be made of the effect of magnesium sulphate on the serum potassium concentration after admin istration of suxamethonium.