Pypendop B H, Verstegen J P
Department of Small Animal Reproduction, School of Veterinary Medicine, University of Liege, Belgium.
Vet Surg. 1998 Nov-Dec;27(6):612-22. doi: 10.1111/j.1532-950x.1998.tb00539.x.
To characterize the hemodynamic effects of medetomidine administered intravenously at doses ranging from 1 to 20 microg/kg, and to determine whether these effects are dose dependent.
Prospective randomized multidose trial.
Twenty-five clinically normal male beagles (5 groups of 5), aged 1 to 4 years and weighing 13.5 +/- 1.7 kg.
Medetomidine, at a dose of 1, 2, 5, 10, or 20 microg/kg, was administered intravenously at time 0. Heart rate, arterial pressure, central venous pressure, mean pulmonary arterial pressure, pulmonary capillary wedge pressure, body temperature, cardiac output, and packed cell volume were measured immediately before and at selected times after medetomidine administration (3, 7, 10, 20, 30, 40, 50, and 60 minutes in all groups, at 90 minutes for the 10 and 20 microg/kg groups, and at 120 minutes for the highest dose). Cardiac index, stroke index, rate-pressure product, systemic vascular resistance index, pulmonary vascular resistance index, and left and right ventricular stroke work indices were calculated. The degree of sedation was subjectively scored by an observer who was blinded to the treatment used.
Heart rate, rate-pressure product, cardiac index, and left and right ventricular stroke work indices decreased below baseline values. Central venous pressure and systemic vascular resistance index increased above baseline measurements. Except in the 2 microg/kg group, after an initial and short lasting increase, a prolonged decrease in arterial pressure was observed.
Hemodynamic changes were observed with the intravenous (IV) administration of medetomidine, at any dose. However, the two lowest doses (1 and 2 microg/kg) produced less cardiovascular depression.
Medetomidine is an alpha-2 adrenoceptor agonist widely used in dogs, producing sedation, analgesia and cardiovascular depression. When using IV medetomidine, a reduction of the recommended dosage (ie, +/-30 to 40 microg/kg) by up to 6 times did not significantly influence the cardiovascular effects.
描述静脉注射剂量范围为1至20微克/千克的美托咪定的血流动力学效应，并确定这些效应是否具有剂量依赖性。
前瞻性随机多剂量试验。
25只临床正常的雄性比格犬（5组，每组5只），年龄1至4岁，体重13.5±1.7千克。
在时间点0静脉注射剂量为1、2、5、10或20微克/千克的美托咪定。在美托咪定给药前及给药后的选定时间（所有组均为给药后3、7、10、20、30、40、50和60分钟，10和20微克/千克组为90分钟，最高剂量组为120分钟）测量心率、动脉压、中心静脉压、平均肺动脉压、肺毛细血管楔压、体温、心输出量和红细胞压积。计算心脏指数、每搏指数、心率-血压乘积、全身血管阻力指数、肺血管阻力指数以及左右心室每搏功指数。由对所用治疗不知情的观察者对镇静程度进行主观评分。
心率、心率-血压乘积、心脏指数以及左右心室每搏功指数降至基线值以下。中心静脉压和全身血管阻力指数高于基线测量值。除2微克/千克组外，在初始短暂升高后，观察到动脉压出现持续下降。
静脉注射美托咪定，无论何种剂量，均观察到血流动力学变化。然而，两个最低剂量（1和2微克/千克）引起的心血管抑制较小。
美托咪定是一种广泛用于犬的α2肾上腺素能受体激动剂，可产生镇静、镇痛和心血管抑制作用。静脉使用美托咪定时，将推荐剂量（即±30至40微克/千克）降低多达6倍对心血管效应无显著影响。
