Ondansetron and long QTc syndrome

Scenario overview EMS and the father bring in 10-month-old boy who has a 2-day history of vomiting and diarrhea. Child has not been tolerating oral fluids today, has had a low-grade fever and has been oliguric. The child has a normal birth/development history and no prior medical history other than congenital deafness. They saw their PMD shortly prior to arrival, who gave the child a medication unknown to the parent (oral ondansetron [Zofran]) and sent the child to the ED for further evaluation. Examination reveals a lethargic child who is actively vomiting, tachycardic and with dry mucous membranes. The father continues to ask the providers to “Do something” and give his child something for the vomiting. Once given ondansetron in the ED along with fluids, the patient becomes unresponsive and goes into cardiac arrest. The team needs to recognize torsades and give magnesium to obtain ROSC. It is later learned that the child has a family history of prolonged QT. Teaching objectives/discussion points Clinical and medical management.