Achôa Renato Viccário, Vane Luiz Antonio, Braz José Reinaldo Cerqueira
CET/SBA do Departamento de Anestesiologia da Faculdade de Medicina de Botucatu (FMB-UNESP), Botucatu, SP.
Rev Bras Anestesiol. 2003 Sep;53(5):610-22.
Infrarenal aortic cross-clamping is associated to cardiovascular effects. Clonidine, an alpha2-agonist, determines bradycardia and hypotension. This study aimed at analyzing the effects of clonidine on the cardiovascular function of dogs submitted to infrarenal aortic cross-clamping.
This randomized study involved 16 mixed breed dogs randomly distributed in two groups: G Control - no clonidine; and G Clon - clonidine (5 microg kg(-1)) immediately before aortic cross-clamping, followed by 2 microg min(-1) m(2) until the end of the study. All dogs were submitted to infrarenal aortic cross-clamping during 45 minutes. Hemodynamic parameters were measured at control (C), 10 (Ao10) and 25 (Ao25) minutes after aortic cross-clamping, and 10 (DAo10) and 25 (DAo25) minutes after aortic unclamping.
There were significant differences between groups in heart rate, mean blood pressure and cardiac index (G control > G Clon) during aortic cross-clamping. After aortic unclamping there were significant differences between groups in heart rate (G Control > G Clon), and right atrium and pulmonary capillary wedge pressures (G Clon > G Control). During aortic cross-clamping both groups have shown significant increase in right atrium pressure, pulmonary capillary wedge pressure, stroke volume index and left ventricular systolic work index, and significant decrease in pulmonary vascular resistance index. There has been significant increase in mean blood pressure, pulmonary artery pressure, cardiac index and right ventricular systolic work index in the G Control. The clonidine group has shown significant heart rate decrease. After aortic unclamping, both groups have shown significant heart rate and mean blood pressure decrease, while right atrium pressure and stroke volume index remained high. Right ventricular systolic work index remained high in the control group, while cardiac index values returned to close to baseline values. In the clonidine group, right atrium pressure, pulmonary wedge pressure and systolic index remained significantly high.
In dogs under our experimental conditions, continuous intravenous clonidine has attenuated cardiovascular responses to infrarenal aortic cross-clamping.
肾下主动脉阻断与心血管效应相关。可乐定作为一种α2受体激动剂，可引起心动过缓和低血压。本研究旨在分析可乐定对接受肾下主动脉阻断的犬心血管功能的影响。
本随机研究纳入16只杂种犬，随机分为两组：对照组（G Control）——未使用可乐定；可乐定组（G Clon）——在主动脉阻断前即刻给予可乐定（5μg kg⁻¹），随后以2μg min⁻¹ m²持续给药直至研究结束。所有犬均接受45分钟的肾下主动脉阻断。在主动脉阻断前（C）、主动脉阻断后10分钟（Ao10）和25分钟（Ao25）以及主动脉松开后10分钟（DAo10）和25分钟（DAo25）测量血流动力学参数。
在主动脉阻断期间，两组在心率、平均血压和心脏指数方面存在显著差异（对照组＞可乐定组）。主动脉松开后，两组在心率方面存在显著差异（对照组＞可乐定组），在右心房和肺毛细血管楔压方面也存在显著差异（可乐定组＞对照组）。在主动脉阻断期间，两组的右心房压力、肺毛细血管楔压、每搏量指数和左心室收缩作功指数均显著升高，肺血管阻力指数显著降低。对照组的平均血压、肺动脉压、心脏指数和右心室收缩作功指数显著升高。可乐定组的心率显著降低。主动脉松开后，两组的心率和平均血压均显著降低，而右心房压力和每搏量指数仍保持较高水平。对照组的右心室收缩作功指数仍保持较高水平，而心脏指数值恢复至接近基线值。在可乐定组，右心房压力、肺楔压和收缩指数仍显著升高。
在我们的实验条件下，持续静脉输注可乐定可减轻犬对肾下主动脉阻断的心血管反应。
