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Anaesthesia and the QT interval. Effects of isoflurane and halothane in unpremedicated children
D Michaloudis1, O Fraidakis, A Petrou
1Anaesthesiology Department, University Hospital, Iraklion, Crete, Greece.
Insights
This study found isoflurane prolonged the QT interval in children, while halothane shortened it. Halothane may be safer for pediatric anesthesia in children with prolonged QT intervals.
Area of Science:
- Pediatric Anesthesiology
- Cardiovascular Pharmacology
Background:
- The QT interval, a measure of cardiac repolarization, is critical for cardiac electrical stability.
- Understanding the effects of anesthetic agents on the QT interval is crucial for patient safety, especially in pediatric populations.
Purpose of the Study:
- To compare the effects of isoflurane and halothane on the QT interval during pediatric anesthesia induction.
- To evaluate the safety and efficacy of these agents in children, particularly those with potential QT interval abnormalities.
Main Methods:
- A study involving 51 unpremedicated, ASA grade 1 children undergoing anesthesia.
- Induction with either isoflurane (n=25) or halothane (n=26) at 2.5%-3% end-tidal concentrations.
- Electrocardiograph, heart rate, and blood pressure monitored at multiple time points, including pre-induction, post-anesthetic stabilization, vecuronium administration, and tracheal intubation.
Main Results:
- Isoflurane significantly prolonged the QT interval (p < 0.001), whereas halothane shortened it (p < 0.01).
- Heart rate remained stable with isoflurane but decreased with halothane (p < 0.001).
- Systolic blood pressure decreased significantly in both groups (p < 0.001). ECG repolarization abnormalities and arrhythmias were observed in both groups, with more arrhythmias in the halothane group.
Conclusions:
- Halothane demonstrated a QT interval-shortening effect, contrasting with isoflurane's prolonging effect in children.
- Halothane may be a preferable anesthetic agent over isoflurane for pediatric patients with prolonged QT intervals.
- Despite observed repolarization changes and arrhythmias, no adverse sequelae were reported in this study.
Abstract:
The effects of isoflurane and halothane on the QT interval were investigated during induction of anaesthesia. Fifty-one unpremedicated, ASA grade 1 children were studied. Anaesthesia was induced with either isoflurane (n = 25) or halothane (n = 26) and was maintained to the end of the study with end-tidal concentrations of between 2.5% and 3%. Recording of the electrocardiograph, heart rate and systolic arterial pressure were obtained at the following times: before induction of anaesthesia; 1 min and 3 min after stable end-tidal concentrations of anaesthetic agent had been reached; 1 min and 3 min following vecuronium administration; at the time of tracheal intubation and 1 min and 3 min later. Isoflurane significantly prolonged the QT interval (p < 0.001), in contrast to halothane which shortened it (p < 0.01). Heart rate remained largely unchanged during isoflurane anaesthesia but it decreased in the presence of halothane (p < 0.001). In both groups, systolic arterial pressure decreased significantly after induction of anaesthesia (p < 0.001) and remained so to the end of the study. In the isoflurane group, 12 children developed ECG repolarisation abnormalities and in one child an arrhythmia was noticed. In the halothane group, one child developed repolarisation changes while arrhythmias were observed in 10 children. There were no adverse sequelae. It is concluded that halothane may be a better anaesthetic agent than isoflurane for use in children with a prolonged QT interval.