title: Anesthetic and cardiovascular effects of balanced anesthesia using constant rate infusion of midazolam-ketamine-medetomidine with inhalation of oxygen-sevoflurane (MKM-OS anesthesia) in horses.
abstract: The anesthetic sparring and cardiovascular effects produced by midazolam 0.8 mg/ml-ketamine 40 mg/ml-medetomidine 0.05 mg/ml (0.025 ml/kg/hr) drug infusion during sevoflurane in oxygen (MKM-OS) anesthesia was determined in healthy horses. The anesthetic sparring effects of MKM-OS were assessed in 6 healthy thoroughbred horses in which the right carotid artery was surgically relocated to a subcutaneous position. All horses were intubated and ventilated with oxygen using intermittent positive pressure ventilation (IPPV). The end-tidal concentration of sevoflurane (ET(SEV)) required to maintain surgical anesthesia was approximately 1.7%. Heart rate and mean arterial blood pressure averaged 23-41 beats/min and 70-112 mmHg, respectively. All horses stood between 23-44 min after the cessation of all anesthetic drugs. The cardiovascular effects of MKM-OS anesthesia were evaluated in 5 healthy thoroughbred horses ventilated using IPPV. Anesthesia was maintained for 4 hr at an ET(SEV) of 1.7%. Each horse was studied during left lateral (LR) and dorsal recumbency (DR) with a minimum interval between evaluations of 1 month. Cardiac output and cardiac index were maintained between 70-80% of baseline values during LR and 65-70% of baseline values during DR. Stroke volume was maintained between 75-85% of baseline values during LR and 60-70% of baseline values during DR. Systemic vascular resistance was not different from baseline values regardless of position. MKM-OS anesthesia may be useful for prolonged equine surgery because of its minimal cardiovascular depression in both of lateral and dorsal recumbency.
authors.affiliation: Department of Small Animal Clinical Sciences, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido, Japan.
authors.forename: Tokiko
authors.initials: T
authors.lastname: Kushiro
authors.forename: Kazuto
authors.initials: K
authors.lastname: Yamashita
authors.forename: Mohammed Ahmed
authors.initials: MA
authors.lastname: Umar
authors.forename: Seiya
authors.initials: S
authors.lastname: Maehara
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Wakaiki
authors.forename: Reona
authors.initials: R
authors.lastname: Abe
authors.forename: Takahiro
authors.initials: T
authors.lastname: Seno
authors.forename: Keiko
authors.initials: K
authors.lastname: Tsuzuki
authors.forename: Yasuharu
authors.initials: Y
authors.lastname: Izumisawa
authors.forename: William W
authors.initials: WW
authors.lastname: Muir
mesh_terms: D000769:Anesthesia, Inhalation / Q000662:veterinary*; D000771:Anesthesia, Intravenous / Q000662:veterinary*; D019162:Anesthetics, Combined / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002245:Carbon Dioxide / Q000378:metabolism; D002302:Cardiac Output / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D006736:Horses / Q000502:physiology* / Q000601:surgery; D007385:Intermittent Positive-Pressure Ventilation; D007649:Ketamine / Q000008:administration & dosage / Q000494:pharmacology; D020926:Medetomidine / Q000008:administration & dosage / Q000494:pharmacology; D008738:Methyl Ethers / Q000008:administration & dosage / Q000494:pharmacology; D008874:Midazolam / Q000008:administration & dosage / Q000494:pharmacology; D010100:Oxygen / Q000008:administration & dosage / Q000378:metabolism; D012119:Respiration / Q000187:drug effects; D000077149:Sevoflurane
chemical_list: D019162:Anesthetics, Combined; D008738:Methyl Ethers; D002245:Carbon Dioxide; D000077149:Sevoflurane; D007649:Ketamine; D020926:Medetomidine; D008874:Midazolam; D010100:Oxygen