title: Cardiovascular function during maintenance of anaesthesia with isoflurane or alfaxalone infusion in greyhounds experiencing blood loss.
abstract: OBJECTIVE
  To compare adequacy of oxygen delivery and severity of shock during maintenance of anaesthesia with isoflurane or alfaxalone infusion in greyhounds experiencing blood loss.
  
  
  METHODS
  Prospective, randomised study.
  
  
  METHODS
  Twenty-four greyhounds (ASA I).
  
  
  METHODS
  All greyhounds were premedicated with methadone (0.2 mg kg(-1) ) intramuscularly. Anaesthesia was induced with alfaxalone 2.5 mg kg(-1) intravenously. Following endotracheal intubation, the dogs were connected to an anaesthetic circle circuit delivering oxygen. Dogs were allocated to receive inhaled isoflurane or an intravenous infusion of alfaxalone for maintenance of anaesthesia. Isoflurane was initially administered to achieve an end-tidal concentration of 1.4% and alfaxalone was initially administered at 0.13 mg kg(-1)  minute(-1) . The dose of isoflurane or alfaxalone was adjusted during instrumentation to produce a clinically equivalent depth of anaesthesia. All dogs were mechanically ventilated to normocapnia (Pa CO2 35-40 mmHg; 4.67-5.33 kPa). Passive warming maintained core body temperature between 37 and 38 °C. Measured and calculated indices of cardiovascular function, including mean arterial blood pressure (MAP), cardiac index (CI), systemic vascular resistance index (SVRI), oxygen delivery index (D˙O2I), oxygen consumption index (V˙O2I) and oxygen extraction ratio (OER), were determined at baseline (60 minutes after start of anaesthesia) and after removal of 32 mL kg(-1) and 48 mL kg(-1) of blood.
  
  
  RESULTS
  In all dogs, blood loss resulted in a significant decrease in MAP, CI, D˙O2 , and a significant increase in SVRI, V˙O2I , and OER. The changes in each of the indices did not differ significantly between dogs receiving isoflurane and dogs receiving alfaxalone.
  
  
  CONCLUSIONS
  No difference in oxygen delivery or severity of shock was observed when either inhaled isoflurane or intravenous alfaxalone infusion was used for maintenance of anaesthesia in greyhounds experiencing blood loss. There appears to be no clinical advantage to choosing one anaesthetic agent for maintenance of anaesthesia over the other in a dog experiencing blood loss.
authors: College Of Veterinary Medicine, Murdoch University, Perth, WA, Australia.
authors: Anthea L
authors: AL
authors: Raisis
authors: Lisa
authors: L
authors: Smart
authors: Eleanor
authors: E
authors: Drynan
authors: Giselle
authors: G
authors: Hosgood
mesh_terms: D000758:Anesthesia / Q000662:veterinary*; D000769:Anesthesia, Inhalation / Q000009:adverse effects / Q000662:veterinary*; D000771:Anesthesia, Intravenous / Q000009:adverse effects / Q000662:veterinary*; D018685:Anesthetics, Inhalation / Q000009:adverse effects; D018686:Anesthetics, Intravenous / Q000009:adverse effects; D000818:Animals; D016063:Blood Loss, Surgical / Q000662:veterinary*; D002320:Cardiovascular Physiological Phenomena / Q000187:drug effects*; D004283:Dog Diseases / Q000503:physiopathology / Q000601:surgery; D004285:Dogs / Q000502:physiology / Q000601:surgery*; D005260:Female; D007262:Infusions, Intravenous / Q000662:veterinary; D007530:Isoflurane / Q000009:adverse effects; D008297:Male; D011277:Pregnanediones / Q000009:adverse effects
chemical_list: D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D011277:Pregnanediones; C006477:alphaxalone; D007530:Isoflurane
keywords: alfaxalone; anaesthesia; blood loss; haemorrhage; isoflurane