Brodbelt D C, Harris J, Taylor P M
Department of Clinical Veterinary Medicine, University of Cambridge, UK.
Res Vet Sci. 1998 Sep-Oct;65(2):119-23. doi: 10.1016/s0034-5288(98)90162-x.
This study investigated whether maintenance of normotension using a methoxamine infusion would prevent activation of the stress response during halothane anaesthesia in ponies. After acepromazine premedication, anaesthesia was induced with thiopentone in six ponies, and maintained for 120 minutes with halothane in oxygen and ventilation to normocapnia. Methoxamine (M, 0.013+/-0.005 mg kg(-1) min(-1)) or saline (C) was infused throughout anaesthesia. Sequential blood samples were taken for cortisol and ACTH assay. During anaesthesia normotension (mean arterial blood pressure 101-124 mm Hg) was maintained in M, whilst hypotension developed in C (nadir 71+/-12 mm Hg). Cardiac output decreased in both groups but to a greater extent in M. Systemic vascular resistance increased more in M (max 2015+/-650 dyne.s cm(-5)) than C (max 939+/-285 dyne.s cm(-5)). Plasma cortisol increased in both groups but more slowly in M. Plasma ACTH did not change in either group. Maintenance of normotension via increased systemic vascular resistance did not prevent, but may have attentuated, the adrenocortical response to anaesthesia. Reduced cardiac output and presumed compromise to tissue perfusion appear as important a stimulus as hypotension. The equine stress response to halothane anaesthesia is likely to be multifactorial.
本研究调查了使用甲氧明输注维持血压正常是否能预防小马在氟烷麻醉期间应激反应的激活。在给予乙酰丙嗪进行术前用药后，6匹小马用硫喷妥钠诱导麻醉，并用氟烷在氧气中维持麻醉120分钟，并通气至正常碳酸血症。在整个麻醉过程中输注甲氧明（M，0.013±0.005 mg·kg⁻¹·min⁻¹）或生理盐水（C）。依次采集血样进行皮质醇和促肾上腺皮质激素检测。麻醉期间，M组维持血压正常（平均动脉血压101 - 124 mmHg），而C组出现低血压（最低点71±12 mmHg）。两组的心输出量均下降，但M组下降幅度更大。M组的全身血管阻力增加幅度（最大值2015±650 dyn·s·cm⁻⁵）大于C组（最大值939±285 dyn·s·cm⁻⁵）。两组血浆皮质醇均升高，但M组升高较慢。两组血浆促肾上腺皮质激素均未改变。通过增加全身血管阻力维持血压正常并不能预防，反而可能减弱了肾上腺皮质对麻醉的反应。心输出量降低以及推测的组织灌注受损似乎与低血压一样是重要的刺激因素。马对氟烷麻醉的应激反应可能是多因素的。
