Case: 69 year old male admitted to ICU for community acquired pneumonia and did well with treatment. Over last 24 hours received Thorazine for persistent hiccups. While revewing morning EKG, you noticed following changes?
Answer: Phenothiazines induced EKG changes.
Phenothiazines induced EKG changes seen in approximately 50% of patients receiving "therapeutic" doses.
- Mimics hypokalemia
- Prominent U waves
- Low amplitude T waves or T wave inversion
- ST segment depression
- Prolonged QT interval
Phenothiazines include Chlorpromazine hydrochloride (Thorazine), Prochlorperazine (Compazine), Promethazine hydrochloride (Phenergan) , Thioridazine hydrochloride (Mellaril) , Trifluoperazine hydrochloride (Stelazine) and others
