Raju S, Hudson C A, Fredericks R, Neglén P, Greene A B, Meydrech E F
Department of Surgery, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216-4505, USA.
Eur J Vasc Endovasc Surg. 1999 Jun;17(6):521-32. doi: 10.1053/ejvs.1999.0818.
to explore the hydrodynamic mechanisms involved in the regulation of ambulatory venous pressure.
an experimental model of calf venous pump was constructed with collapsible tubes and valves.
the model consisted of a conduit and a pump with an intervening competent valve. Another valve that could allow reflux into the pump was mounted above the pump.
conduit pressure and recovery times were monitored under conditions of different degrees of ejection fraction and reflux into the pump. Model variables included using poorly compliant tubes for the pump, the conduit and for both the pump and conduit.
the latex tube exhibited a non-linear volume-pressure relationship and a bi-modal regimen of compliance. This bestowed pressure-buffering properties. Ambulatory venous hypertension resulted when reflux beyond buffering capacity occurred. Substituting less compliant PTFE for latex at the pump had a relatively minor effect on post-ejection pressure and recovery times. Using PTFE at the conduit had a profound but divergent effect on both of these parameters. Conduit capacitance reduction had a similar effect.
conduit elastance plays a significant role in the regulation of ambulatory venous pressure in this experimental model. The hydrodynamic principles illustrated by the model may enhance our understanding of the human calf venous pump.
探讨参与调节动态静脉压的流体动力学机制。
用可塌陷的管道和瓣膜构建小腿静脉泵的实验模型。
该模型由一个管道和一个带有中间有效瓣膜的泵组成。另一个允许血液回流到泵内的瓣膜安装在泵的上方。
在不同射血分数和血液回流到泵内的情况下监测管道压力和恢复时间。模型变量包括在泵、管道或泵与管道两者中使用顺应性差的管道。
乳胶管呈现非线性的容积-压力关系和双模式顺应性状态。这赋予了压力缓冲特性。当回流超过缓冲能力时会导致动态静脉高压。在泵处用顺应性较小的聚四氟乙烯替代乳胶对射血后压力和恢复时间的影响相对较小。在管道处使用聚四氟乙烯对这两个参数有显著但不同的影响。管道电容减小也有类似影响。
在该实验模型中，管道弹性在调节动态静脉压方面起重要作用。该模型所阐明的流体动力学原理可能会增进我们对人体小腿静脉泵的理解。
