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44599 - THE EFFECT OF PROPOFOL DOSE ON MYOCARDIAL REPOLARIZATION IN CHILDREN

¹ BC Children’s Hospital, Vancouver, BC, Canada
² BC Children’s Hospital
³ BC Children’s hospital
⁴ BC Children’s
⁵ BC Children’s

Abstract

Introduction: Acquired QT interval prolongation on the ECG is commonly drug-induced, and is traditionally associated with torsades de pointes (TdP). A better predictor of TdP is the time interval between the peak and the end of the T wave (Tp-e)(1). Sevoflurane prolongs the corrected QT interval (QTc), although the Tp-e remains unaffected(2). In contrast, target controlled infusion of propofol at 3 µg/mL has no effect on QTc or Tp-e. This plasma concentration of propofol is at the extreme lower end of the range for surgical anesthesia. The purpose of this randomised double-blind clinical study was to investigate the dose-response relationship between propofol, QTc and Tp-e in a range of doses clinically relevant for surgical anesthesia.

Methods: Written ethics committee approval and consent was obtained. 60 healthy unpremedicated children, aged 3–10 years, were recruited. Subjects were randomised to receive target controlled infusions of propofol, to achieve one of three plasma concentrations: 3µg/mL, 4.5µg/mL and 6µg/mL. A pre-operative 12 lead ECG was performed and repeated 5 minutes post induction. Two investigators, blinded to the group allocation and to the timing of the ECG traces, independently measured QTc and Tp-e within and between each group. Paired t-tests were used to compare QTc and Tp-e within groups. One way analysis of variance was used for inter-group analysis. The primary outcome measure was a change of >25msec in Tp-e both within and between groups.

Results: ECG recordings were obtained in 52 children. There were no demographic or ECG differences at baseline. There were no differences in QTc or Tp-e post induction within or between the 3 different groups (see table).

REFERENCES

1 Yan G, Antzelevitch C. Cellular basis for the normal T wave and the electrocardiographic manifestations of the long-QT syndrome Circulation 1998; 98:1928–36

2 Whyte S, Booker P, Buckley D. The effects of propofol and sevoflurane on the QT interval and transmural dispersion of repolarisation in children Anesth Analg 2005;100:71–77