D. Michaloudis et al., ANESTHESIA AND THE QT INTERVAL - EFFECTS OF ISOFLURANE AND HALOTHANE IN UNPREMEDICATED CHILDREN, Anaesthesia, 53(5), 1998, pp. 435-439
The effects of isoflurane and halothane on the QT interval were invest
igated during induction of anaesthesia. Fifty-one unpremedicated, ASA
grade 1 children were studied. Anaesthesia was induced with either iso
flurane (n = 25) or halothane (n = 26) and was maintained to the end o
f the study with end-tidal concentrations of between 2.5% and 3%. Reco
rdings of the electrocardiograph, heart rate and systolic arterial pre
ssure were obtained at the following times: before induction of anaest
hesia; 1 min and 3 min after stable end-tidal concentrations of anaest
hetic agent had been reached; 1 min and 3 min following vecuronium adm
inistration; at the time of tracheal intubation and 1 min and 3 min la
ter. Isoflurane significantly prolonged the QT interval (p < 0.001), i
n contrast to halothane which shortened it (p < 0.01). Heart rate rema
ined largely unchanged during isoflurane anaesthesia but it decreased
in the presence of halothane (p < 0.001). In bath groups, systolic art
erial 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 1
0 children. There were no adverse sequelae. It is concluded that halot
hane may be a better anaesthetic agent than isoflurane for use in chil
dren with a prolonged QT interval.