UMEM Educational Pearls

What they did:

  • End stage renal disease (ESRD) patients presenting to the ED for emergent hemodialysis (HD) with baseline QTc prolongation (>450 msec in men and >470 msec in women) were given antiemetics or antihistamines for symptomatic relief of nausea and pruritis. A repeat ECG was obtained 2 hours after medications were given.
  • Most patients received oral or intravenous promethazine 25 mg, ondansetron 4-8 mg, or diphenhydramine 25-50 mg.

What they found:

  • 44 patients had a mean initial QTc of 483.7 msec (SD 18.4). Two hours after medication administration, the mean QTc was 483.8 msec (SD 20.0).
  • Among 13 patients with initial QTc intervals >500 msec, 9 had an increased QTc interval after medication administration (average increase 11.8 msec, SD 6.7 msec).
  • 8 patients with baseline QTc <500 msec had QTc >500 msec after medication administration.
  • No patients experienced dysrhythmias, death, or were admitted for dysrhythmia or syncope 1 week after medication administration.

Application to clinical practice:

  • While the mean QTc did not change, the proportion of individuals who experienced an increase in QTc interval is not reported.
  • Although greatly limited by a small sample size, this study suggests that usual doses of promethazine, ondansetron, or diphenhydramine in patients presenting for emergent HD with baseline QTc prolongation may be safe.
  • Additional studies, especially in patients with QTc prolongation >500 msec, are warranted.


Burdette S, Roppolo LP, Green W, et al. The effect of antiemetics and antihistamines on the QTc interval in emergent dialysis patients with baseline QTc prolongation. J Emerg Med 2016; 51:99-105. (PMID 27614302)

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