Mama K R, Steffey E P, Pascoe P J
Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis 95616-8745, USA.
Am J Vet Res. 1996 Apr;57(4):512-6.
To evaluate selected hemodynamic, respiratory, and behavioral responses to propofol in horses premedicated with xylazine or detomidine.
Xylazine (0.5 and 1.0 mg/kg of body weight) was administered IV on different days to each of 6 horses prior to IV administration of propofol (2 mg/kg). In a second group of 6 horses, detomidine (15 and 30 micrograms/kg) was similarly studied.
2 groups of 6 mature healthy horses.
Rectal temperature, heart and respiratory rates, arterial blood gas tensions, and direct arterial blood pressures were recorded before and at fixed intervals after drug administration. Induction and recovery events were quantitatively and qualitatively assessed. Cardiopulmonary and behavioral data to follow were statistically analyzed (P < or = 0.05).
Heart rate decreased in dose-dependent manner from a mean (+/- SD) of 39.5 +/- 5.1 beats/min after xylazine and detomidine. Second-degree atrioventricular dissociation was commonly seen at the higher drug doses. After propofol administration, heart rate either transiently increased or was less depressed early in recumbency, compared with predrug values. Direct arterial blood pressures varied inconsistently from predrug values. Mean arterial carbon dioxide tension tended to increase after drug administration (significance variable) from predrug values of 42 to 46 mm of Hg in both drug groups. After xylazine or detomidine administration, arterial oxygen tension decreased significantly from predrug values of 97 to 103 mm of Hg. The magnitude and duration of decrease was dose-dependent and greatest during recumbency. Behavioral responses to anesthetic induction were variable, but horses were uniformly calm and coordinated during recovery. Recumbency time increased in response to the higher dose of either premedicant drug. Mean (+/- SD) times to standing were 25.02 +/- 4.42 and 35.57 +/- 6.83 minutes for the low and high doses of xylazine, respectively and 41.04 +/- 11.21 and 52.64 +/- 14.67 minutes for the low and high doses of detomidine, respectively.
Neither xylazine nor detomidine prevented excitation associated with propofol injection in horses.
Xylazine or detomidine-propofol combinations likely will not replace common anesthetic induction techniques for horses. However, recovery characteristics associated with propofol encourage further study in horses.
评估用赛拉嗪或地托咪定预处理的马匹对丙泊酚的血流动力学、呼吸及行为反应。
在6匹马静脉注射丙泊酚（2mg/kg）前，于不同日期分别静脉注射赛拉嗪（0.5和1.0mg/kg体重）。在另一组6匹马中，同样研究了地托咪定（15和30μg/kg）。
2组，每组6匹成熟健康马匹。
在给药前及给药后固定时间间隔记录直肠温度、心率、呼吸频率、动脉血气张力及直接动脉血压。对诱导和苏醒过程进行定量和定性评估。对后续的心肺及行为数据进行统计学分析（P≤0.05）。
赛拉嗪和地托咪定给药后，心率以剂量依赖性方式从平均（±标准差）39.5±5.1次/分钟下降。在较高药物剂量时常见二度房室传导阻滞。与给药前值相比，丙泊酚给药后，心率在卧姿早期要么短暂升高，要么下降幅度较小。直接动脉血压与给药前值相比变化不一致。两组给药后平均动脉二氧化碳张力均有从给药前42mmHg升至46mmHg的趋势（差异有统计学意义）。赛拉嗪或地托咪定给药后，动脉血氧张力从给药前97至103mmHg显著下降。下降幅度和持续时间呈剂量依赖性，且在卧姿时最大。对麻醉诱导的行为反应各异，但马匹在苏醒过程中均保持安静且协调。较高剂量的任何一种预处理药物均可使卧姿时间延长。低剂量和高剂量赛拉嗪的平均（±标准差）站立时间分别为25.02±4.42分钟和35.57±6.83分钟，低剂量和高剂量地托咪定的平均站立时间分别为41.04±11.21分钟和52.64±14.67分钟。
赛拉嗪和地托咪定都不能预防马匹丙泊酚注射相关的兴奋反应。
赛拉嗪或地托咪定-丙泊酚联合用药可能无法取代马匹常用的麻醉诱导技术。然而丙泊酚相关的苏醒特性值得在马匹中进一步研究。
