Comparison of the effects of xylazine bolus versus medetomidine constant rate infusion on cardiopulmonary function and depth of anesthesia in horses anesthetized with isoflurane

Abstract

In isoflurane-anesthetized horses, premedication with medetomidine followed by administration of medetomidine as a constant rate infusion resulted in decreased heart rate, higher arterial blood pressure from 20 through 40 minutes after induction of anesthesia, and better preserved body temperature, compared with conventional treatment with xylazine. Greater depth of anesthesia and muscle relaxation were seen with MCRI treatment, despite the lower isoflurane concentration.

Effects of Medetomidine Constant Rate Infusion on Sevoflurane Requirement, Cardiopulmonary Function, and Recovery Quality in Thoroughbred Racehorses Undergoing Arthroscopic Surgery

“…In the previous comparison study of 1.7% of isoflurane versus 1.4% of isoflurane with medetomidine CRI, administration of medetomidine as CRI preserved more brisk eye reflexes when horses were maintained at 20%-30% lower inhalant anesthetic concentration, although the horses were at a similar plane of anesthesia during both treatments [13,20]. Traditionally, the depth of anesthesia in horses has been evaluated on the basis of ocular signs, such as spontaneous palpebral reflex and nystagmus.…”

“…It was reported that medetomidine CRI reduced the minimum alveolar concentration (MAC) of desflurane by 28% in experimental ponies [16]. Others reported that isoflurane anesthesia in combination with medetomidine CRI resulted in improved cardiopulmonary function, analgesia, and muscle relaxation [13,15]. However, sevoflurane sparing effect of medetomidine CRI under surgical procedure has not been investigated in clinical cases.…”

“…The short half-life of medetomidine and its selectivity and potency are suitable to be used as a constant rate infusion (CRI) for balanced anesthesia in horses [12][13][14][15]. It was reported that medetomidine CRI reduced the minimum alveolar concentration (MAC) of desflurane by 28% in experimental ponies [16].…”

The cardiovascular status of isoflurane-anaesthetized horses with and without dexmedetomidine constant rate infusion evaluated at equivalent depths of anaesthesia

“…; Creighton et al. ). Dexmedetomidine is an α 2 ‐agonist with a pharmacokinetic profile that suggests it is suitable for administration as a CRI (Bettschart‐Wolfensberger et al.…”

Effects of continuous rate infusion of butorphanol in isoflurane-anesthetized calves

“…Although BIS was originally designed for human subjects, studies have demonstrated its usefulness in anesthetic procedures in other species [10][11][12][13][14][15] . To the author's knowledge, limited data characterizing BIS in bovines have been published.…”