D. Michaloudis et al., Anaesthesia and the QT interval in humans: effects of halothane and isoflurane in premedicated children, EUR J ANAES, 15(6), 1998, pp. 623-628
The effects of halothane and isoflurane followed by subsequent administrati
on of vecuronium on the QT interval have been investigated during the induc
tion of anaesthesia. Fifty-eight children, ASA I, without cardiovascular an
d electrolyte abnormalities and not receiving any medication were studied.
Anaesthesia was induced with either halothane (n = 28) or isoflurane (n = 3
0), and was maintained until the end of the study with end-tidal concentrat
ions of 2.5-3%. Recordings of EGG, heart rate and systolic arterial pressur
e were obtained at the following times: prior to induction of anaesthesia;
1 and 3 min after stable end-tidal concentrations of the induction agent ha
d been reached; 1 and 3 min following vecuronium administration; at the tim
e of tracheal intubation; 1 and 3 min later. Halothane significantly shorte
ned the QTc interval (P < 0.05); isoflurane prolonged it (P < 0.001). Heart
rate decreased significantly after halothane administration (P < 0.01); in
contrast, heart rate increased after induction of anaesthesia with isoflur
ane (P < 0.05), increasing fur ther after laryngoscopy and tracheal intubat
ion (P < 0.001). Systolic arterial pressure decreased significantly (P < 0.
001) in both groups after induction of anaesthesia and remained decreased u
ntil the end of the study. It is concluded that halothane may be a better c
hoice than isoflurane for children with a long QT interval.