Pharmacotherapy
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Droperidol and haloperidol have demonstrated efficacy and safety in the treatment of acute delirium in critically ill patients. We conducted MEDLINE and manual searches of literature published from 1966-1996 to identify articles describing conduction disturbances associated with the drugs. The objectives were to describe the proposed mechanisms of acquired long QTc interval syndrome and torsades de pointes, and to recommend how critically ill patients receiving these agents should be monitored. ⋯ If the baseline QTc interval is 440 msec or longer, and they are receiving other drugs that may prolong the QTc interval or they have electrolyte disturbances, a butyrophenone antipsychotic should be prescribed with caution. All critically ill patients receiving droperidol or haloperidol should undergo electrocardiogram monitoring and QTc interval measurement; special attention should be given to those receiving doses greater than 50 mg/24 hours, as these patients appear to be at greatest risk for development of conduction disturbances. Based on the currently available literature, in any critically ill patient receiving droperidol or haloperidol therapy whose QTc interval lengthens by 25% or more over baseline, therapy should be discontinued or the dosage reduced.
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Torsades de pointes is a polymorphic ventricular tachycardia characterized by marked QT prolongation on the electrocardiogram. It can be induced by both antiarrhythmic and nonantiarrhythmic drugs, such as quinidine and erythromycin. ⋯ He developed torsades de pointes and subsequently cardiac arrest. Since erythromycin and quinidine are known to cause arrhythmias individually, caution and close monitoring are necessary when the drugs are administered concomitantly.