Anaesthetic and cardiorespiratory effects of a constant-rate infusion of alfaxalone in desflurane-anaesthetised sheep.
A prospective, randomised, blinded controlled study was performed to determine the anaesthetic and cardiorespiratory effects of a constant-rate infusion (CRI) of alfaxalone in 12 sheep anaesthetised with desflurane, and undergoing experimental orthopaedic surgery. Sheep were sedated with dexmedetomidine (4 μg/kg, intravenously) and butorphanol (0.3 mg/kg, intravenously). Anaesthesia was induced with alfaxalone (1 mg/kg/minute to effect, intravenously) and maintained with desflurane in oxygen and alfaxalone 0.07 mg/kg/minute or saline for 150 minutes (range 150-166 minutes). The anaesthetic induction dose of alfaxalone, the desflurane expiratory fraction required for anaesthetic maintenance, cardiorespiratory measurements and blood-gases were recorded at predetermined intervals. Quality of sedation, anaesthetic induction and recovery were assessed. The alfaxalone induction dose was 1.7 mg/kg (1.2 to 2.6 mg/kg). The desflurane expiratory fraction was lower (22 per cent) in sheep receiving alfaxalone CRI (P=0). Also, heart rate (P=0), cardiac index (P=0.002), stroke index (P=0) and contractility (P=0) were higher, and systemic vascular resistance (P=0.002) was lower. Although respiratory rate tended to be higher with alfaxalone, there was no difference in PCO2 between the groups. Recovery times were significantly longer in sheep given alfaxalone (25.4 v 9.5 minutes) but recovery quality was similar. Alfaxalone reduced requirements of desflurane and maintained similar cardiorespiratory function, but recovery time was more prolonged.
Department of Animal Medicine and Surgery, Anaesthesia Unit, Veterinary Faculty, University of Córdoba, Córdoba, Spain. pv2grmam@uco.es
M M
MM
Granados
J M
JM
Domínguez
A
A
Fernández-Sarmiento
F J
FJ
Funes
J
J
Morgaz
R
R
Navarrete
J M
JM
Carrillo
M
M
Rubio
P
P
Muñoz-Rascón
I A
IA
Gómez de Segura
R
R
Gómez-Villamandos
D000777:Anesthetics / Q000008:administration & dosage / Q000494:pharmacology*; D018685:Anesthetics, Inhalation / Q000008:administration & dosage; D000818:Animals; D001784:Blood Gas Analysis; D001831:Body Temperature / Q000187:drug effects; D000077335:Desflurane; D004305:Dose-Response Relationship, Drug; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D007263:Infusions, Parenteral / Q000662:veterinary; D007530:Isoflurane / Q000008:administration & dosage / Q000031:analogs & derivatives; D011277:Pregnanediones / Q000008:administration & dosage / Q000494:pharmacology*; D011446:Prospective Studies; D012119:Respiration / Q000187:drug effects; D012756:Sheep / Q000502:physiology*; D013997:Time Factors
D000777:Anesthetics; D018685:Anesthetics, Inhalation; D011277:Pregnanediones; C006477:alphaxalone; D000077335:Desflurane; D007530:Isoflurane