title: Anaesthesia and the QT interval in humans: effects of halothane and isoflurane in premedicated children.
abstract: The effects of halothane and isoflurane followed by subsequent administration of vecuronium on the QT interval have been investigated during the induction of anaesthesia. Fifty-eight children, ASA I, without cardiovascular and electrolyte abnormalities and not receiving any medication were studied. Anaesthesia was induced with either halothane (n = 28) or isoflurane (n = 30), and was maintained until the end of the study with end-tidal concentrations of 2.5-3%. Recordings of ECG, heart rate and systolic arterial pressure were obtained at the following times: prior to induction of anaesthesia; 1 and 3 min after stable end-tidal concentrations of the induction agent had been reached; 1 and 3 min following vecuronium administration; at the time of tracheal intubation; 1 and 3 min later. Halothane significantly shortened 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 isoflurane (P < 0.05), increasing further after laryngoscopy and tracheal intubation (P < 0.001). Systolic arterial pressure decreased significantly (P < 0.001) in both groups after induction of anaesthesia and remained decreased until the end of the study. It is concluded that halothane may be a better choice than isoflurane for children with a long QT interval.
authors.affiliation: Anaesthetic Department, University Hospital, Crete, Greece.
authors.forename: D
authors.initials: D
authors.lastname: Michaloudis
authors.forename: O
authors.initials: O
authors.lastname: Fraidakis
authors.forename: T
authors.initials: T
authors.lastname: Lefaki
authors.forename: F
authors.initials: F
authors.lastname: Kanakoudis
authors.forename: H
authors.initials: H
authors.lastname: Askitopoulou
mesh_terms: D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D002675:Child, Preschool; D004562:Electrocardiography / Q000187:drug effects*; D005260:Female; D006221:Halothane / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D006993:Hypnotics and Sedatives / Q000008:administration & dosage; D007223:Infant; D007530:Isoflurane / Q000494:pharmacology*; D008133:Long QT Syndrome / Q000503:physiopathology; D008297:Male; D008874:Midazolam / Q000008:administration & dosage; D003473:Neuromuscular Nondepolarizing Agents / Q000494:pharmacology; D011229:Preanesthetic Medication; D014673:Vecuronium Bromide / Q000494:pharmacology
chemical_list: D018685:Anesthetics, Inhalation; D006993:Hypnotics and Sedatives; D003473:Neuromuscular Nondepolarizing Agents; D014673:Vecuronium Bromide; D007530:Isoflurane; D008874:Midazolam; D006221:Halothane