Role of halothane in QT-time prolongation and dysrhythmias during microlaryngoscopy.
To study the mechanism of dysrhythmias during microlaryngoscopy, heart rate-corrected QT-times (QTc) were measured in three different methods of anaesthesia. A balanced anaesthesia was induced by Althesin in 96 patients, or by thiopentone in 68 patients. Halothane anaesthesia was induced by Althesin in 23 patients. In all groups the mean QTc-time was significantly longer during the manipulation of vocal cords than before the induction of anaesthesia. Dysrhythmias are also most common during the procedure. With the Althesin-halothane combination, however, the prolongation of QTc-time was most pronounced: Control X +/- SE 408.4 +/- 5.5 msec, manipulation 432.3 +/- 6.7 msec, p less than 0.001. Among those patients who had dysrhythmias during the procedure, only the patients in the Althesin-halothane group had significantly longer QTc-time than before anaesthesia. In patients with supra-ventricular dysrhythmias, differences of QTc-time did not reach significant level. Significant prolongation of QTc-time occurred in patients with ventricular ectopic beats (p less than 0.05) and junctional rhythm (p less than 0.02) but only in the Althesin-halothane group.
D000328:Adult; D000530:Alfaxalone Alfadolone Mixture / Q000494:pharmacology; D000758:Anesthesia / Q000379:methods; D001145:Arrhythmias, Cardiac / Q000139:chemically induced*; D004338:Drug Combinations; D004562:Electrocardiography; D005260:Female; D006221:Halothane / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007828:Laryngoscopy / Q000379:methods; D008297:Male; D008875:Middle Aged; D013874:Thiopental / Q000494:pharmacology
D004338:Drug Combinations; D000530:Alfaxalone Alfadolone Mixture; D013874:Thiopental; D006221:Halothane