USE OF PROPANIDID AND LIGNOCAINE TO MODIFY THE INCREASE IN SERUM POTASSIUM CONCENTRATION FOLLOWING INJECTION OF SUXAMETHONIUM

A technique of general anaesthesia involving the use of propanidid, nitrous oxide, oxygen and halothane followed by a slow injection of suxamethonium and lignocaine is described. The technique decreased the increase in serum potassium concentration that follows the injection of suxamethonium and,it is suggested, possesses advantagesoverthe existing practice of the injection of non-depolarizing neuromuscular blocking drugs before suxamethonium in an attempt to reduce the frequency of serious cardiac arrhythmia. The i.v. injection of suxamethonium 50 mg has been shown to increase the serum concentration of potassium by 0.2-0.4 mmol litre"1 (Bah", Dundee and Assaf, 1975). The author has described previously a technique of general anaesthesia that decreases the frequency and force of fasciculations after suxa-methonium (Fry, 1975a) and the frequency and severity of the subsequent muscle pains (Fry, 1975b). Propanidid was followed by nitrous oxide, oxygen and halothane until spontaneous breathing was estab-lished, when a mixture of lignocaine 0.75 mg kg"1 and suxamethonium 0.35 mg kg"1 was injected slowly i.v. The results of the present study suggest that the technique modifies the increase in the serum potas-sium following suxamethonium. METHODS One hundred consecutive patients were anaesthetized by the author and received a single dose of suxa-methonium to facilitate tracheal intubation. The patients were divided randomly into two groups (control and lignocaine). Control group. 22 males, average age 41.2 (SD 17.6) yr, range 16-76 yr; 28 females, average age 46.6 (SD 21.8) yr, range 12-85 yr. Lignocaine group. 24 males, average age 40.9 (SD 19.6) yr, range 15-70 yr; 26 females, average age 44.5 (SD 21.8) yr, range 12-84 yr. There were no statistically significant differences between the two groups. All the patients were premedicated with metoclo-pramide 20 mg and diazepam 20 mg orally approxi-mately 90 min before operation