QT prolongation in the intensive care unit: commonly used medications and the impact of drug-drug interactions.
ABSTRACT Critically ill patients are at an increased risk to develop drug-drug interactions (DDIs). DDIs that increase the risk of QT prolongation, and ultimately torsades de pointes, can result in a medical emergency. Many clinicians are unaware of the risk of certain drug combinations that may precipitate QT prolongation in the intensive care unit (ICU). Additional DDI education and a review of management strategies could assist with prevention of future adverse outcomes.
This review focuses on some commonly used medications in the ICU that may be involved in pharmacokinetic and/or pharmacodynamic DDIs leading to the development of QT prolongation and possibly torsades de pointes. Also, appropriate management strategies are discussed.
The ICU clinician will gain a better understanding of common medications used in the ICU and DDIs that put patients at risk for the development of QT prolongation and torsades de pointes.
Medications that may cause QT prolongation are common in the ICU and DDIs need to be identified and prevented by the clinician to avoid a potentially life-threatening dysrrhythmia.
- SourceAvailable from: J. Philip Miller[show abstract] [hide abstract]
ABSTRACT: Abnormal cardiac repolarization, indicated by a prolongation of the QT interval, increases the risk for torsades de pointes, a potentially life-threatening arrhythmia. Many perioperatively administered drugs and conditions prolong the QT interval. Despite several reports of perioperative torsades de pointes, systematic evidence regarding perioperative QT interval prolongation is limited. Serial postoperative 12-lead electrocardiograms were obtained from 469 adult patients undergoing major noncardiac surgery under general anesthesia. Heart rate corrected QT-interval duration (Fridericia formula) was the primary outcome. All perioperatively administered drugs were recorded. Emphasis was placed on absolute QTc prolongation greater than 500 ms and relative increases of 30 and 60 ms. At the end of surgery, 80% of the patients (345 of 429) experienced a significant QTc interval prolongation (ΔQTc 23 ± 26 ms (mean and SD), 95% CI 20-25 ms, P less than 0.001). Approximately 51% (219 of 429) had a QTc greater than 440 ms, and 4% (16 of 429) a QTc greater than 500 ms. In 39% (166 of 429), the ΔQTc was greater than 30 ms, in 8% (34 of 429) >60 ms, and in greater than 0.5% (2 of 429) >100 ms. No changes in ΔQTc occurred at subsequent time points. One patient developed torsades de pointes with a ΔQTc: 29 ms (0.4% incidence rate). Several drugs had a large effect on ΔQTc: isoflurane, methadone, ketorolac, cefoxitin, zosyn, unasyn, epinephrine, ephedrine, and calcium. Postoperative body temperature had a weak negative correlation with ΔQTc (r = -0.15, P = 0.02); serum magnesium, potassium, and calcium concentrations were not correlated. Postoperative QT-interval prolongation is common. Several perioperatively administered drugs are associated with a substantial QT-interval prolongation. The exact cause and its clinical relevance are, however, unclear. Nevertheless, an association between postoperative QT prolongation and risk for torsades de pointes is likely.Anesthesiology 06/2012; 117(2):321-8. · 5.16 Impact Factor