James Lauren E, Williams Catherine Ja, Bertelsen Mads F, Wang Tobias
Section for Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark.
Section for Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark.
Vet Anaesth Analg. 2018 May;45(3):329-337. doi: 10.1016/j.vaa.2017.12.003. Epub 2018 Jan 9.
To characterise the minimum dose of intramuscular alfaxalone required to facilitate intubation for mechanical ventilation, and to investigate the impact of cranial versus caudal injection on anaesthetic depth.
Randomised crossover study.
Six healthy juvenile ball pythons (Python regius).
Three dosages (10, 20 and 30 mg kg) of alfaxalone were administered to each python in a caudal location with a minimum 2 weeks washout. Induction and recovery were monitored by assessing muscle tone, righting reflex, response to a noxious stimulus and the ability to intubate. A subsequent experiment assessed the influence of injection site by comparing administration of 20 mg kg alfaxalone in a cranial location (1 cm cranial to the heart) with the caudal site. Respiration rate was monitored throughout, and when intubation was possible, snakes were mechanically ventilated.
Regardless of dose and injection site, maximum effect was reached within 10.0 ± 2.7 minutes. When administered at the caudal injection site, intubation was only successful after a dosage of 30 mg kg-, which is higher than in previous reports for other reptiles. However, intubation was possible in all cases after 7.2 ± 1.6 minutes upon cranial administration of 20 mg kg, and anaesthetic duration was significantly lengthened (p < 0.001). Both 30 mg kg at the caudal site and 20 mg kg at the cranial site led to apnoea approximately 10 minutes post-injection, at which time the snakes were intubated and mechanically ventilated.
Alfaxalone provided rapid, smooth induction when administered intramuscularly to pythons, and may serve as a useful induction agent prior to provision of volatile anaesthetics. The same dosage injected in the cranial site led to deeper anaesthesia than when injected caudally, suggesting that shunting to the liver and first-pass metabolism of alfaxalone occur when injected caudally, via the renal portal system.
确定肌内注射阿法沙龙以促进机械通气插管所需的最小剂量，并研究头侧注射与尾侧注射对麻醉深度的影响。
随机交叉研究。
6条健康的幼年球蟒（皇蟒）。
给每条蟒蛇在尾侧部位注射三种剂量（10、20和30mg/kg）的阿法沙龙，洗脱期至少为2周。通过评估肌张力、翻正反射、对有害刺激的反应和插管能力来监测诱导和恢复情况。随后的实验通过比较在头侧部位（心脏头侧1cm处）注射20mg/kg阿法沙龙与尾侧部位注射的效果，评估注射部位的影响。全程监测呼吸频率，当可以插管时，对蛇进行机械通气。
无论剂量和注射部位如何，在10.0±2.7分钟内达到最大效果。在尾侧注射部位给药时，仅在剂量为30mg/kg后插管才成功，这一剂量高于先前关于其他爬行动物的报道。然而，在头侧给予20mg/kg后，所有情况下在7.2±1.6分钟后都可以插管，并且麻醉持续时间显著延长（p<(0.001)）。尾侧部位注射30mg/kg和头侧部位注射20mg/kg均在注射后约10分钟导致呼吸暂停，此时对蛇进行插管并机械通气。
阿法沙龙肌内注射给蟒蛇时能提供快速、平稳的诱导，并且在使用挥发性麻醉剂之前可能是一种有用的诱导剂。在头侧部位注射相同剂量比在尾侧注射导致更深的麻醉，这表明尾侧注射时阿法沙龙通过肾门静脉系统分流至肝脏并发生首过代谢。
