title: Comparison of cardiorespiratory variables in dorsally recumbent horses anesthetized with guaifenesin-ketamine-xylazine spontaneously breathing 50% or maximal oxygen concentrations.
abstract: This study compared cardiorespiratory variables in dorsally recumbent horses anesthetized with guaifenesin-ketamine-xylazine and spontaneously breathing 50% or maximal (> 90%) oxygen (O2) concentrations. Twelve healthy mares were randomly assigned to breathe 50% or maximal O2 concentrations. Horses were sedated with xylazine, induced to recumbency with ketamine-diazepam, and anesthesia was maintained with guaifenesin-ketamine-xylazine to effect. Heart rate, arterial blood pressures, respiratory rate, lithium dilution cardiac output (CO), inspired and expired O2 and carbon dioxide partial pressures, and tidal volume were measured. Arterial and mixed-venous blood samples were collected prior to sedation (baseline), during 30 minutes of anesthesia, 10 minutes after disconnection from O2, and 30 minutes after standing. Shunt fraction, O2 delivery, and alveolar-arterial O2 partial pressures difference [P(A-a)O2] were calculated. Recovery times were recorded. There were no significant differences between groups in cardiorespiratory parameters or in P(A-a)O2 at baseline or 30 minutes after standing. Oxygen partial pressure difference in the 50% group was significantly less than in the maximal O2 group during anesthesia.
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, 601 Vernon L. Tharp Street, Columbus, Ohio 43210, USA.
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Karrasch
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, 601 Vernon L. Tharp Street, Columbus, Ohio 43210, USA.
authors.forename: John A E
authors.initials: JA
authors.lastname: Hubbell
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, 601 Vernon L. Tharp Street, Columbus, Ohio 43210, USA.
authors.forename: Turi K
authors.initials: TK
authors.lastname: Aarnes
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, 601 Vernon L. Tharp Street, Columbus, Ohio 43210, USA.
authors.forename: Richard M
authors.initials: RM
authors.lastname: Bednarski
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, 601 Vernon L. Tharp Street, Columbus, Ohio 43210, USA.
authors.forename: Phillip
authors.initials: P
authors.lastname: Lerche
mesh_terms: D000778:Anesthetics, Dissociative / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure; D002245:Carbon Dioxide / Q000097:blood; D002302:Cardiac Output / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005100:Expectorants / Q000008:administration & dosage / Q000494:pharmacology; D005260:Female; D006140:Guaifenesin / Q000008:administration & dosage / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D006736:Horses / Q000502:physiology*; D006993:Hypnotics and Sedatives / Q000008:administration & dosage / Q000494:pharmacology; D007649:Ketamine / Q000008:administration & dosage / Q000494:pharmacology*; D010100:Oxygen / Q000008:administration & dosage* / Q000097:blood; D011187:Posture; D012119:Respiration / Q000187:drug effects; D014991:Xylazine / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D000778:Anesthetics, Dissociative; D005100:Expectorants; D006993:Hypnotics and Sedatives; D002245:Carbon Dioxide; D014991:Xylazine; D006140:Guaifenesin; D007649:Ketamine; D010100:Oxygen
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