title: Effect of alfaxalone infusion on the electroencephalogram of dogs anaesthetized with halothane.
abstract: OBJECTIVE
  To describe the effects of alfaxalone on the canine electroencephalogram (EEG).
  
  
  METHODS
  Experimental study.
  
  
  METHODS
  Eight healthy adult Huntaway dogs.
  
  
  METHODS
  Anaesthesia was induced with propofol and maintained with halothane (0.85-0.95 end-tidal volume %) in oxygen. Animals were ventilated to maintain stable end-tidal CO(2) and halothane concentrations. Following a 30 minute stabilisation period, alfaxalone (0.5 mg kg(-1) ) was infused intravenously over a 5 minute period. The electroencephalogram was recorded from the beginning of the stabilisation period until 60 minutes following the start of alfaxalone treatment. Data were subjected to fast Fourier transformation, and median frequency, 95% spectral edge frequency and total EEG power were calculated. Two-factorial repeated measures anova (time and EEG channels were factors) was used for statistical analysis (p < 0.05).
  
  
  RESULTS
  A shift in the dominant frequency band from beta to delta after alfaxalone treatment and occasional burst suppression were observed. Median frequency decreased significantly below baseline (9.2 ± 1.4 Hz) (mean ± SD) during alfaxalone infusion. The lowest value (4.8 ± 1.2 Hz) was recorded 5 minutes after the start of infusion. Spectral edge frequency also decreased below baseline (26.2 ± 1.5 Hz) and the lowest value (22.6 ± 1.5 Hz) also was detected at 5 minutes after the start of infusion. Total EEG power did not change significantly. In some frequencies EEG power increased soon after the start of alfaxalone infusion, then decreased below baseline later (biphasic pattern).
  
  
  CONCLUSIONS
  Alfaxalone induced biphasic changes on EEG and decreased F(50) and F(95) in halothane anaesthetized dogs.
authors: Institute of Veterinary, Animal and Biomedical Sciences, College of Sciences, Massey University, Palmerston North, New Zealand. tamas.ambrisko@vetmeduni.ac.at
authors: Tamas D
authors: TD
authors: Ambrisko
authors: Craig B
authors: CB
authors: Johnson
authors: Paul
authors: P
authors: Chambers
mesh_terms: D000769:Anesthesia, Inhalation / Q000662:veterinary*; D000771:Anesthesia, Intravenous / Q000662:veterinary*; D000777:Anesthetics / Q000008:administration & dosage / Q000494:pharmacology*; D018685:Anesthetics, Inhalation; D000818:Animals; D004285:Dogs / Q000502:physiology*; D004569:Electroencephalography / Q000187:drug effects / Q000662:veterinary*; D005260:Female; D006221:Halothane; D008297:Male; D011277:Pregnanediones / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D000777:Anesthetics; D018685:Anesthetics, Inhalation; D011277:Pregnanediones; C006477:alphaxalone; D006221:Halothane