Total intravenous anesthesia with alfaxalone, dexmedetomidine and remifentanil in healthy foals undergoing abdominal surgery

Teela Jones; José L Bracamonte; Barbara Ambros; Tanya Duke-Novakovski

doi:10.1016/j.vaa.2019.01.003

Total intravenous anesthesia with alfaxalone, dexmedetomidine and remifentanil in healthy foals undergoing abdominal surgery

Vet Anaesth Analg. 2019 May;46(3):315-324. doi: 10.1016/j.vaa.2019.01.003. Epub 2019 Jan 22.

Authors

Teela Jones¹, José L Bracamonte², Barbara Ambros³, Tanya Duke-Novakovski²

Affiliations

¹ Department of Small Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada. Electronic address: tlj333@mail.usask.ca.
² Department of Small Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada.
³ Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada.

PMID: 30846290
DOI: 10.1016/j.vaa.2019.01.003

Abstract

Objective: To evaluate effects of anesthesia induced with alfaxalone and maintained with alfaxalone, dexmedetomidine and remifentanil infusions in foals.

Study design: Prospective, experimental study.

Animals: A group of six healthy foals [median (range) 11 (8-33) days] undergoing abdominal surgery.

Methods: Intravenous (IV) dexmedetomidine (3-7μgkg^-1) provided sedation for insertion of a pulmonary artery catheter. IV anesthesia was induced with alfaxalone (2mgkg^-1) and maintained with alfaxalone (6mgkg^-1hour^-1), dexmedetomidine (1μgkg^-1hour^-1) and remifentanil (3μgkg^-1hour^-1). Foals were endotracheally intubated and lungs were mechanically ventilated with oxygen. Cardiac output (thermodilution), heart rate and systemic arterial pressure were measured. Arterial and mixed venous blood was analyzed for PO₂ and PCO₂, and glucose, lactate and electrolyte concentrations. Anesthetic depth was subjectively assessed. Systemic vascular resistance (SVR), oxygen utilization and intrapulmonary shunt were calculated. Preinduction (PB) or 10 minutes postinduction (+10B) data were used as baselines with one-way analysis of variance for repeated measures. Data are mean ± standard deviation; significance was p ≤ 0.05.

Results: Duration of anesthesia was 129 ± 22minutes. One foal was administered additional alfaxalone (0.5mgkg^-1) following induction. Cardiac index decreased to 107 ± 31 and 87 ± 21mLkg^-1minute^-1 at 60 and 80minutes, respectively, compared with PB (157 ± 33mLkg^-1minute^-1). SVR increased to 1223 ± 166dynessecond^-1cm^-5 at 80minutes compared with +10B (704 ± 247dynessecond^-1cm^-5). Mean arterial pressures were 63-128mmHg. Time from stopping infusions to standing was 46-106minutes. All foals were hypothermic (<36°C) and three foals were administered atipamezole (0.05mgkg^-1) intramuscularly during recovery.

Conclusion: and clinical relevance Combined alfaxalone-dexmedetomidine-remifentanil provided suitable anesthesia to permit laparotomy in foals. At the doses evaluated, prolonged recovery may occur.

Keywords: alfaxalone; dexmedetomidine; foal; remifentanil; total intravenous anesthesia.

MeSH terms

Anesthesia, Intravenous / veterinary*
Anesthetics, Combined / administration & dosage*
Animals
Dexmedetomidine / administration & dosage*
Female
Horses / surgery*
Laparotomy / veterinary*
Male
Pregnanediones / administration & dosage*
Prospective Studies
Remifentanil / administration & dosage*

Substances

Anesthetics, Combined
Pregnanediones
Dexmedetomidine
alphaxalone
Remifentanil