Myocardial specific creatine phosphokinase isoenzyme elevation in children with asthma treated with intravenous isoproterenol

We retrospectively reviewed admissions that required intravenous (IV) isoproterenol in an intensive care unit setting for management of severe childhood status asthmaticus. Elevation of the cardiac-specific serum creatine phosphokinase MB (CPK-MB) isoenzyme was noted in 15 of 19 admissions. The mean peak elevation of serum CPK in those 15 admissions was 204 IU/L with a mean peak MB band of 6.05%. Nine of the 15 admissions with elevated CPK-MB level had follow-up levels measured after IV isoproterenol had been stopped. In all nine cases, the follow-up serum CPK-MB level was 0%. In six of those nine cases, follow-up serum with undetectable CPK-MB level was obtained while the patients continued to receive IV aminophylline and corticosteroids, and inhaled but not intravenous β-adrenergic agonist medications. These observations suggest that elevated serum CPK-MB levels that may be indicative of myocardial injury are associated with IV isoproterenol therapy of severe childhood asthma. Therefore, we recommend caution along with serial monitoring of serum CPK-MB levels when IV isoproterenol is administered in the therapy of childhood asthma.