Evaluation of five common induction protocols by comparison of hemodynamic responses to surgical manipulation in halothane-anesthetized horses

Ann E. Wagner From the Department of Clinical Sciences (Wagner, Dunlop, Wertz), College of Veterinary Medicine and Biomedical Sciences, and the Department of Statistics (Chapman), Colorado Stale University, Fort Collins, CO 80523.

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 DVM, MS
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Colin I. Dunlop From the Department of Clinical Sciences (Wagner, Dunlop, Wertz), College of Veterinary Medicine and Biomedical Sciences, and the Department of Statistics (Chapman), Colorado Stale University, Fort Collins, CO 80523.

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Etta M. Wertz From the Department of Clinical Sciences (Wagner, Dunlop, Wertz), College of Veterinary Medicine and Biomedical Sciences, and the Department of Statistics (Chapman), Colorado Stale University, Fort Collins, CO 80523.

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Philip L. Chapman From the Department of Clinical Sciences (Wagner, Dunlop, Wertz), College of Veterinary Medicine and Biomedical Sciences, and the Department of Statistics (Chapman), Colorado Stale University, Fort Collins, CO 80523.

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 PhD

Design—

To determine whether hemodynamic responses of halothane-anesthetized horses undergoing surgical procedures depended on anesthetic induction protocols used, and to determine whether hemodynamic responses to surgical manipulation could be detected.

Design—

Prospective experimental study without controls.

Animals—

36 clinically normal horses.

Procedure—

Horses were allotted to 5 groups according to anesthetic induction protocol: acepromazine/guaifene-sin/thiamylal, acepromazine/guaifenesin/ketamine, xyla-zine/guaifenesin/thiamylal, xylazine/guaifenesin/ketamine, and xylazine/diazepam/ketamine. Anesthesia was maintained with halothane. Hemodynamic measurements and blood gas values were obtained prior to the start of surgery, during surgery, and after surgery.

Results—

Few differences in hemodynamic measurements existed between horses in which anesthesia was induced by 5 anesthetic induction protocols, whether prior to the start of surgery or for pooled values for all 3 measurement periods. Hemodynamic responses to surgical manipulation were marked and included increased mean arterial pressure and systemic vascular resistance, and decreased cardiac index and oxygen delivery.

Clinical Implications—

Choice of anesthetic induction protocol has little impact on hemodynamic function during surgery in halothane-anesthetized horses. Surgical stimulation may increase blood pressure, but does not improve cardiac index or oxygen delivery. (J Am Vet Med Assoc 1996;208:252-257)

Design—

To determine whether hemodynamic responses of halothane-anesthetized horses undergoing surgical procedures depended on anesthetic induction protocols used, and to determine whether hemodynamic responses to surgical manipulation could be detected.

Design—

Prospective experimental study without controls.

Animals—

36 clinically normal horses.

Procedure—

Horses were allotted to 5 groups according to anesthetic induction protocol: acepromazine/guaifene-sin/thiamylal, acepromazine/guaifenesin/ketamine, xyla-zine/guaifenesin/thiamylal, xylazine/guaifenesin/ketamine, and xylazine/diazepam/ketamine. Anesthesia was maintained with halothane. Hemodynamic measurements and blood gas values were obtained prior to the start of surgery, during surgery, and after surgery.

Results—

Few differences in hemodynamic measurements existed between horses in which anesthesia was induced by 5 anesthetic induction protocols, whether prior to the start of surgery or for pooled values for all 3 measurement periods. Hemodynamic responses to surgical manipulation were marked and included increased mean arterial pressure and systemic vascular resistance, and decreased cardiac index and oxygen delivery.

Clinical Implications—

Choice of anesthetic induction protocol has little impact on hemodynamic function during surgery in halothane-anesthetized horses. Surgical stimulation may increase blood pressure, but does not improve cardiac index or oxygen delivery. (J Am Vet Med Assoc 1996;208:252-257)

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