Factitious lowering of the serum potassium level after cardiopulmonary resuscitation. Implications for evaluating the arrhythmogenicity of hypokalemia in acute myocardial infarction.

Hypokalemia has been suggested as a predisposing factor to the development of fatal arrhythmias in acute myocardial infarction. Evidence cited to support this concept has been derived largely from studies in which the determination of the serum potassium level was made following a cardiac arrhythmia and/or arrest, and often following cardiopulmonary resuscitation (CPR); this postresuscitation potassium level has been considered to be representative of the prearrest value. In the patient described herein, serial determinations of serum potassium obtained fortuitously before and intentionally following sudden unexpected cardiac arrest in a hospitalized patient demonstrate that the prearrest serum potassium level cannot be inferred from electrolyte values obtained after CPR.