Incidence and causes of hypokalemia associated with cardiac resuscitation

To further investigate the incidence and etiology of hypokalemia during cardiac arrest, the authors compared data on 74 adult nontrauma cardiac arrest patients (44 men, 30 women, age 65 +/- 13 years) who had a serum potassium (K+) level documented during or immediately following resuscitation with data on 53 adult controls with life-threatening medical emergencies presenting to the emergency department who did not experience arrest. Hypokalemia (serum K+ less than 3.6 mEq/l) occurred in 25 arrest patients (34%) compared with nine controls (17%). Serum K+ was not significantly different shortly before (3.7 +/- 0.4) versus immediately after arrest (3.6 +/- 0.8) in a small subgroup of patients, making intracellular shifting of K+ because of metabolic events during resuscitation an unlikely etiology. Hypokalemia was associated with a 2.5-fold increase in relative risk for cardiac arrest. Patients who were receiving diuretics without K+ supplementation had the highest risk of arrest (4.4-fold increase). Supplementation of K+ appeared to be protective in patients on diuretics. The authors confirm the association between hypokalemia and cardiac arrest and suggest that this metabolic abnormality may be an important risk factor for cardiac arrest.