[The Interaction of Low-dose Droperidol, Propofol, and Sevoflurane on QTc Prolongation].

BACKGROUND: Droperidol is an effective antiemetic, but its use is limited because of the warning of drug-induced QT prolongation. Some reports showed that low-dose droperidol does not significantly probing QT interval. This study was aimed to determine the effect of low-dose droperidol (1.25 and 2.5 mg) on QTc interval, and the interaction among droperidol, propofol and sevoflurane.

METHODS: Patients received either 1.25 mg (group L : n = 25) or 2.5 mg (group H : n = 25) droperidol, and fentanyl (3 μg x kg(-1)) was administered 2.5 min later. One minute after fentanyl administration, anesthesia was induced using propofol (1.5 mg x kg(-1)) and vecuronium. One minute after propofol administration, sevoflurane (3%) was started. Tracheal intubation was performed 3 min after propofol administration, and then sevoflurane was reduced to 1%.

RESULTS: Compared to baseline, the QTc interval in group L was unchanged by droperidol. In group H, the QTc interval was significantly prolonged after droperidol injection, but recovered after propofol injection. After tracheal intubation, QTc interval was significantly prolonged in both groups.

CONCLUSIONS: Droperidol's effect on QTc prolongation was shown at the dose of 2.5 mg but not 1.25 mg. This prolongation effect was offset by propofol, and was unchanged by sevoflurane.