• calcium salts
• hyperkalaemia

In response to the letter by Dr McMorran¹ we would like to comment on the use of calcium salts in the management of hyperkalaemia.

It is worth reiterating that the two formulations of intravenous calcium have distinct properties. The amount of elemental calcium (Ca²⁺) is 8.9 mg/ml as 10% calcium gluconate and 27.2 mg/ml as 10% calcium chloride solution. The availability of Ca²⁺ may be limited in the calcium gluconate because of chelation, until hepatically metabolised. In haemodynamic instability with poor liver perfusion this might prove significant, hence the recommendation for use of the chloride salt in cardiac arrest. It should be noted, however, that several studies have failed to show differences in availability of ionised calcium even in the anhepatic stage of liver transplantation.²

Although the literature does not provide a definitive answer, we recommend that the chloride salt be used thereby eliminating concern over the possible impact of hepatic metabolism of the gluconate, and avoiding the confusion inherent in having two formulations with different doses on the resuscitation trolley.