Creighton Catherine M, Lemke Kip A, Lamont Leigh A, Horney Barbara S, Riley Christopher B
Departments of Companion Animals, Atlantic Veterinary College, Charlottetown, PE C1A 4P3, Canada.
J Am Vet Med Assoc. 2012 Apr 15;240(8):991-7. doi: 10.2460/javma.240.8.991.
To compare the effects of xylazine bolus versus medetomidine constant rate infusion (MCRI) on cardiopulmonary function and depth of anesthesia in dorsally recumbent, spontaneously breathing, isoflurane-anesthetized horses.
Prospective, randomized crossover study.
10 healthy adult 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. Physiologic data (ie, heart rate, respiratory rate, rectal temperature, bispectral index, and electromyographic values) were compared between treatments with xylazine bolus versus MCRI.
Heart rate was lower, but mean arterial blood pressure was higher from 20 to 40 minutes with MCRI treatment, compared with conventional treatment with xylazine. Respiratory rate and rectal temperature were greater with MCRI treatment. Bispectral index was lower with MCRI treatment from 80 to 150 minutes, and electromyographic values were lower with MCRI treatment from 30 to 150 minutes.
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.
比较在背卧位、自主呼吸、异氟烷麻醉的马匹中，单次注射赛拉嗪与美托咪定持续输注（MCRI）对心肺功能和麻醉深度的影响。
前瞻性、随机交叉研究。
10匹健康成年标准赛马。
马匹静脉注射赛拉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。赛拉嗪治疗时，呼气末异氟烷浓度维持在1.7%，在麻醉结束时静脉推注赛拉嗪（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]）。比较单次注射赛拉嗪与MCRI治疗时的生理数据（即心率、呼吸频率、直肠温度、脑电双频指数和肌电图值）。
与传统的赛拉嗪治疗相比，MCRI治疗在20至40分钟时心率较低，但平均动脉血压较高。MCRI治疗时呼吸频率和直肠温度较高。MCRI治疗在80至150分钟时脑电双频指数较低，在30至150分钟时肌电图值较低。
在异氟烷麻醉的马匹中，与传统的赛拉嗪治疗相比，术前用美托咪定并持续输注美托咪定导致心率降低，麻醉诱导后20至40分钟动脉血压升高，体温保持更好。尽管异氟烷浓度较低，但MCRI治疗的麻醉深度和肌肉松弛效果更佳。
