Rioja Eva, Kerr Carolyn L, Enouri Saad S, McDonell Wayne N
Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada.
Am J Vet Res. 2008 Mar;69(3):319-29. doi: 10.2460/ajvr.69.3.319.
To assess the sedative and cardiopulmonary effects of medetomidine and xylazine and their reversal with atipamezole in calves.
25 calves.
A 2-phase (7-day interval) study was performed. Sedative characteristics (phase I) and cardiopulmonary effects (phase II) of medetomidine hydrochloride and xylazine hydrochloride administration followed by atipamezole hydrochloride administration were evaluated. In both phases, calves were randomly allocated to receive 1 of 4 treatments IV: medetomidine (0.03 mg/kg) followed by atipamezole (0.1 mg/kg; n = 6), xylazine (0.3 mg/kg) followed by atipamezole (0.04 mg/kg; 7), medetomidine (0.03 mg/kg) followed by saline (0.9% NaCl; 6) solution (10 mL), and xylazine (0.3 mg/kg) followed by saline solution (10 mL; 6). Atipamezole or saline solution was administered 20 minutes after the first injection. Cardiopulmonary variables were recorded at intervals for 35 minutes after medetomidine or xylazine administration.
At the doses evaluated, xylazine and medetomidine induced a similar degree of sedation in calves; however, the duration of medetomidine-associated sedation was longer. Compared with pretreatment values, heart rate, cardiac index, and PaO(2) decreased, whereas central venous pressure, PaCO(2), and pulmonary artery pressures increased with medetomidine or xylazine. Systemic arterial blood pressures and vascular resistance increased with medetomidine and decreased with xylazine. Atipamezole reversed the sedative and most of the cardiopulmonary effects of both drugs.
At these doses, xylazine and medetomidine induced similar degrees of sedation and cardiopulmonary depression in calves, although medetomidine administration resulted in increases in systemic arterial blood pressures. Atipamezole effectively reversed medetomidine- and xylazine-associated sedative and cardiopulmonary effects in calves.
评估美托咪定和赛拉嗪对犊牛的镇静及心肺效应，以及用阿替美唑对其进行逆转的效果。
25头犊牛。
进行了一项分两阶段（间隔7天）的研究。评估了盐酸美托咪定和盐酸赛拉嗪给药后再给予盐酸阿替美唑的镇静特性（第一阶段）和心肺效应（第二阶段）。在两个阶段中，犊牛被随机分配接受4种静脉注射治疗中的1种：美托咪定（0.03mg/kg）后给予阿替美唑（0.1mg/kg；n = 6），赛拉嗪（0.3mg/kg）后给予阿替美唑（0.04mg/kg；7），美托咪定（0.03mg/kg）后给予生理盐水（0.9%氯化钠；6）溶液（10mL），赛拉嗪（0.3mg/kg）后给予生理盐水溶液（10mL；6）。在首次注射后20分钟给予阿替美唑或生理盐水溶液。在给予美托咪定或赛拉嗪后，每隔一段时间记录35分钟的心肺变量。
在所评估的剂量下，赛拉嗪和美托咪定在犊牛中诱导出相似程度的镇静；然而，与美托咪定相关的镇静持续时间更长。与预处理值相比，美托咪定或赛拉嗪给药后心率、心脏指数和动脉血氧分压（PaO₂）降低，而中心静脉压、动脉血二氧化碳分压（PaCO₂）和肺动脉压升高。美托咪定使体循环动脉血压和血管阻力增加，赛拉嗪则使其降低。阿替美唑逆转了两种药物的镇静及大部分心肺效应。
在这些剂量下，赛拉嗪和美托咪定在犊牛中诱导出相似程度的镇静和心肺抑制，尽管给予美托咪定会导致体循环动脉血压升高。阿替美唑有效地逆转了美托咪定和赛拉嗪在犊牛中引起的镇静及心肺效应。
