Kuusela E, Raekallio M, Väisänen M, Mykkänen K, Ropponen H, Vainio O
Department of Clinical Veterinary Sciences, Faculty of Veterinary Medicine, University of Helsinki, Finland.
Am J Vet Res. 2001 Jul;62(7):1073-80. doi: 10.2460/ajvr.2001.62.1073.
To compare 3 dose levels of medetomidine and dexmedetomidine for use as premedicants in dogs undergoing propofol-isoflurane anesthesia.
6 healthy Beagles.
Dogs received medetomidine or dexmedetomidine intravenously at the following dose levels: 0.4 microg of medetomidine or 0.2 microg of dexmedetomidine/kg of body weight (M0.4/D0.2), 4.0 microg of medetomidine or 2.0 microg of dexmedetomidine/kg (M4/D2), and 40 microg of medetomidine or 20 microg of dexmedetomidine/kg (M40/D20). Sedation and analgesia were scored before induction. Anesthesia was induced with propofol and maintained with isoflurane. End-tidal isoflurane concentration, heart rate, and arterial blood pressures and gases were measured.
Degrees of sedation and analgesia were significantly affected by dose level but not drug. Combined mean end-tidal isoflurane concentration for all dose levels was higher in dogs that received medetomidine, compared with dexmedetomidine. Recovery time was significantly prolonged in dogs treated at the M40/D20 dose level, compared with the other dose levels. After induction, blood pressure decreased below reference range and heart rate increased in dogs treated at the M0.4/D0.2 dose level, whereas blood pressure was preserved in dogs treated at the M40/D20 dose level. However, dogs in these latter groups developed profound bradycardia and mild metabolic acidosis during anesthesia. Treatment at the M4/D2 dose level resulted in more stable cardiovascular effects, compared with the other dose levels. In addition, PaCO2 was similar among dose levels.
Dexmedetomidine is at least as safe and effective as medetomidine for use as a premedicant in dogs undergoing propofol-isoflurane anesthesia.
比较3种剂量水平的美托咪定和右美托咪定在接受丙泊酚-异氟烷麻醉的犬中作为术前用药的效果。
6只健康的比格犬。
犬静脉注射美托咪定或右美托咪定，剂量水平如下：0.4微克美托咪定或0.2微克右美托咪定/千克体重（M0.4/D0.2）、4.0微克美托咪定或2.0微克右美托咪定/千克（M4/D2）、40微克美托咪定或20微克右美托咪定/千克（M40/D20）。诱导前对镇静和镇痛进行评分。用丙泊酚诱导麻醉并用异氟烷维持。测量呼气末异氟烷浓度、心率、动脉血压和血气。
镇静和镇痛程度受剂量水平显著影响，但不受药物影响。与右美托咪定相比，接受美托咪定的犬所有剂量水平的呼气末异氟烷浓度合并平均值更高。与其他剂量水平相比，接受M40/D20剂量水平治疗的犬恢复时间显著延长。诱导后，接受M0.4/D0.2剂量水平治疗的犬血压降至参考范围以下且心率增加，而接受M40/D20剂量水平治疗的犬血压保持正常。然而，后一组犬在麻醉期间出现严重心动过缓和轻度代谢性酸中毒。与其他剂量水平相比，M4/D2剂量水平治疗导致更稳定的心血管效应。此外，各剂量水平间动脉血二氧化碳分压相似。
在接受丙泊酚-异氟烷麻醉的犬中，右美托咪定作为术前用药至少与美托咪定一样安全有效。
