Hypokalemic periodic paralysis presenting as cardiac arrest.

Hypokalemic periodic paralysis (HPP) is a channelopathy with a genetic predisposition which may occur in the presence or absence of hyperthyroidism. We present a unique case of severe HPP associated with both Grave's thyrotoxicosis and pemphigus vulgaris. The patient developed proximal limb weakness after treatment with rituximab. He then subsequently presented with witnessed ventricular fibrillation arrest. Cardiopulmonary resuscitation was initiated in the field and return of spontaneous circulation was achieved. His initial potassium was 1.9 mmol/L with a marked metabolic acidosis.