title: Anesthetic and cardiopulmonary effects of total intravenous anesthesia using a midazolam, ketamine and medetomidine drug combination in horses.
abstract: The anesthetic and cardiopulmonary effects of midazolam, ketamine and medetomidine for total intravenous anesthesia (MKM-TIVA) were evaluated in 14 horses. Horses were administered medetomidine 5 microg/kg intravenously as pre-anesthetic medication and anesthetized with an intravenous injection of ketamine 2.5 mg/kg and midazolam 0.04 mg/kg followed by the infusion of MKM-drug combination (midazolam 0.8 mg/ml-ketamine 40 mg/ml-medetomidine 0.1 mg/ml). Nine stallions (3 thoroughbred and 6 draft horses) were castrated during infusion of MKM-drug combination. The average duration of anesthesia was 38 +/- 8 min and infusion rate of MKM-drug combination was 0.091 +/- 0.021 ml/kg/hr. Time to standing after discontinuing MKM-TIVA was 33 +/- 13 min. The quality of recovery from anesthesia was satisfactory in 3 horses and good in 6 horses. An additional 5 healthy thoroughbred horses were anesthetized with MKM- TIVA in order to assess cardiopulmonary effects. These 5 horses were anesthetized for 60 min and administered MKM-drug combination at 0.1 ml/kg/hr. Cardiac output and cardiac index decreased to 70-80%, stroke volume increased to 110% and systemic vascular resistance increased to 130% of baseline value. The partial pressure of arterial blood carbon dioxide was maintained at approximately 50 mmHg while the arterial partial pressure of oxygen pressure decreased to 50-60 mmHg. MKM-TIVA provides clinically acceptable general anesthesia with mild cardiopulmonary depression in horses. Inspired air should be supplemented with oxygen to prevent hypoxemia during MKM-TIVA.
authors.affiliation: Department of Small Animal Clinical Sciences, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido, Japan.
authors.forename: Kazuto
authors.initials: K
authors.lastname: Yamashita
authors.forename: Tikiri P
authors.initials: TP
authors.lastname: Wijayathilaka
authors.forename: Tokiko
authors.initials: T
authors.lastname: Kushiro
authors.forename: Mohammed A
authors.initials: MA
authors.lastname: Umar
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Taguchi
authors.forename: William W
authors.initials: WW
authors.lastname: Muir
mesh_terms: D000704:Analysis of Variance; D000762:Anesthesia Recovery Period; D000771:Anesthesia, Intravenous / Q000662:veterinary*; D000818:Animals; D002245:Carbon Dioxide / Q000097:blood; D002302:Cardiac Output / Q000187:drug effects; D004338:Drug Combinations; D006736:Horses / Q000502:physiology*; D007649:Ketamine / Q000494:pharmacology*; D020926:Medetomidine / Q000494:pharmacology*; D008874:Midazolam / Q000494:pharmacology*; D010100:Oxygen / Q000097:blood; D013318:Stroke Volume / Q000187:drug effects; D014655:Vascular Resistance / Q000187:drug effects
chemical_list: D004338:Drug Combinations; D002245:Carbon Dioxide; D007649:Ketamine; D020926:Medetomidine; D008874:Midazolam; D010100:Oxygen