Creighton Catherine M, Lemke Kip A, Lamont Leigh A, Horney Barbara S, Doyle Aimie J
Departments of Companion Animals, Atlantic Veterinary College, Charlottetown, PE C1A 4P3, Canada.
J Am Vet Med Assoc. 2012 Apr 15;240(8):998-1002. doi: 10.2460/javma.240.8.998.
To compare the effect of xylazine bolus versus medetomidine constant rate infusion (MCRI) on serum cortisol and glucose concentrations, urine production, and anesthetic recovery characteristics in dorsally recumbent, spontaneously breathing, isoflurane-anesthetized horses.
Prospective, randomized crossover study.
10 healthy Standardbreds.
Horses were premedicated with xylazine or medetomidine IV. Anesthesia was induced with diazepam and ketamine and maintained with isoflurane for 150 minutes. For the xylazine treatment, end-tidal isoflurane concentration was maintained at 1.7% and xylazine (0.2 mg/kg [0.09 mg/lb]), IV) was administered as a bolus at the end of anesthesia. For the MCRI treatment, end-tidal isoflurane concentration was maintained at 1.4% and medetomidine (0.005 mg/kg/h [0.0023 mg/lb/h], IV) was infused throughout anesthesia. Serum cortisol and glucose concentrations were measured before, during, and after anesthesia. Urine specific gravity and volume were measured during anesthesia. Unassisted anesthetic recoveries were recorded by a digital video camera for later evaluation by 2 observers who were blinded to treatment.
Serum cortisol concentration was lower and serum glucose concentration was higher with MCRI treatment, compared with xylazine treatment. Time to sternal recumbency was longer with MCRI treatment, but no difference was seen between treatments for times to extubation, first movement, or standing. Objective (mean attempt interval) and subjective (visual analog score) recovery scores were significantly better with MCRI treatment, compared with xylazine treatment.
In isoflurane-anesthetized horses, premedication and administration of medetomidine as a constant rate infusion resulted in decreased serum cortisol concentration, increased serum glucose concentration, and superior anesthetic recovery characteristics, compared with conventional treatment with xylazine.
比较甲苯噻嗪推注与美托咪定持续输注（MCRI）对背卧位、自主呼吸、异氟烷麻醉马匹血清皮质醇和葡萄糖浓度、尿量及麻醉恢复特征的影响。
前瞻性、随机交叉研究。
10匹健康的标准赛马。
马匹静脉注射甲苯噻嗪或美托咪定进行术前用药。用安定和氯胺酮诱导麻醉，并用异氟烷维持麻醉150分钟。甲苯噻嗪治疗时，呼气末异氟烷浓度维持在1.7%，在麻醉结束时静脉推注甲苯噻嗪（0.2mg/kg[0.09mg/lb]）。MCRI治疗时，呼气末异氟烷浓度维持在1.4%，在整个麻醉过程中静脉输注美托咪定（0.005mg/kg/h[0.0023mg/lb/h]）。在麻醉前、麻醉期间和麻醉后测量血清皮质醇和葡萄糖浓度。在麻醉期间测量尿比重和尿量。用数码摄像机记录无辅助的麻醉恢复情况，供2名对治疗不知情的观察者稍后评估。
与甲苯噻嗪治疗相比，MCRI治疗的血清皮质醇浓度较低，血清葡萄糖浓度较高。MCRI治疗时达到胸卧位的时间较长，但在拔管时间、首次移动时间或站立时间方面，两种治疗方法之间没有差异。与甲苯噻嗪治疗相比，MCRI治疗的客观（平均尝试间隔）和主观（视觉模拟评分）恢复评分明显更好。
在异氟烷麻醉的马匹中，与传统的甲苯噻嗪治疗相比，术前用药及持续输注美托咪定可降低血清皮质醇浓度，增加血清葡萄糖浓度，并具有更好的麻醉恢复特征。
