Patterns of ionized and total calcium in serum of children following suxamethonium.

Serum ionized and total calcium levels of forty children, aged 3 to 18 years, were studied before and after the administration of suxamethonium during halothane inhalation in 20 children under the age of 10 (group I) and 10 children over the age of 10 (group II), and during intravenous induction of anesthesia with pancuronium and thiopentone in 10 children over the age of 10 (group III). In all groups suxamethonium was followed by a small but significant (p less than 0.02) decrease in the serum ionized calcium concentration. The fall was greater in group I. The serum total calcium concentration was lowered in groups II and III. But the decrease was only significant (p less than 0.001) in group III. In group I, there was a great discrepancy in the changes in serum total calcium concentration ranging from a fall of 0.535 mmol.l-1 to a rise of 0.680 mmol.l-1. The decrease in the total calcium concentration may have been caused by the depolarizing action of suxamethonium leading to the migration of the calcium ions into the muscle cells. But the changes in the ionized calcium concentration are more complex and may involve the movements of this ion in the cells, its binding to the proteins and its complexion to anions.