Feasibility of determining small vessel compliance using Doppler optical coherence tomography.

使用多普勒光学相干断层扫描确定小血管顺应性的可行性。

基本信息

批准号：
EP/E015077/1
负责人：
Stephen Matcher
金额：
$ 21.53万
依托单位：
University of Sheffield
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2007
资助国家：
英国
起止时间：
2007 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FE015077%2F1
关键词：
Feasibility determining small vessel compliance

项目摘要

Perhaps the commonest and simplest medical test one can apply is to 'feel for a pulse'. The sensation of pulsation which we feel through our fingers is a direct consequence of the fact that our bodies are 'plumbed' with flexible tubes which expand and contract in response to blood pumped by the heart. When we are young, our vessels are very elastic and 'compliant'. As we age, they naturally stiffen and if we lead an unhealthy and inactive lifestyle, 'hardening of the arteries' can become life-threatening. Diabetes, one of the commonest diseases in the western world, is associated with just such a loss of 'vascular compliance'. It is therefore of great medical value to be able to measure the compliance of all the important blood vessels in the body.Compliance can be determined rather easily if one can measure the pressure inside a vessel. In this case one can measure the increase in vessel diameter brought about by a known increase in pressure. This works well on vessels that have been removed from the body but is very difficult to apply in a living subject. So physiologists have developed another approach: to measure the speed at which the pulse travels away from the heart. It is well known that sound travels much faster in solid objects like steel than it does in air. This is because steel is much less compressible than air. Sound speed is thus a direct measure of the elastic properties of a solid medium. The same is true in blood vessels, they transmit the arterial pulse from the heart faster if the vessels are stiff than if they are compliant. This idea has been used successfully to measure the compliance of large vessels in the body. However it is of great interest to know about the smallest vessels in the body also i.e. vessels that are 0.2 mm or less in diameter. These vessels form the microcirculation and perform the vital function of actually delivering the oxygen and other nutrients to the cells that need them. In this application we want to explore a new concept for measuring the elastic properties of such small vessels. We will apply a new technique, a form of optical radar , to image the blood flow in these vessels with unprecedented resolution (a few thousands of a millimetre). By carefully measuring how the flow velocity and vessel diameter change together during an arterial pulse, it should be possible to determine the elastic properties of these vessels for the first time in living subjects. In this initial study, we want to test the basis of this idea in a simple idealised system; if encouraging the pilot data will lay the foundations for a fuller investigation.The information that we glean in this way will be important in many ways. In diabetes, for example, loss of vessel compliance leads to a loss of hyperaemic response , whereby ordinarily the body responds to a temporary loss of blood flow with an elevated burst of fresh blood. However it is still not clear whether changes in vessel compliance are a cause or an effect of such diseases. What is known is that diabetes sufferers must endure a host of very unpleasant symptoms whose underlying cause fits very well with the concept of a disturbed blood supply to cells by the microcirculation. The condition known as diabetic foot arises when the nerves in the foot die causing a lack of sensation and associated outbreaks of painful pressure sores. Diabetic retinopathy is creeping blindness caused by death of the nerves in the retina that respond to light. Our research project is a joint collaboration between optical physicists, fluid dynamicists and microvascular physiologists. It aims to apply cutting-edge optical physics and fluid-flow modelling to the task of improving our understanding of diseases of the microcirculation. Ultimately this could lead to the development of better drugs to control the symptoms of microvascular disease and a consequent improvement in the quality of life of millions of sufferers.

也许最常见、最简单的医学测试就是“感觉脉搏”。我们通过手指感受到的脉动感是我们的身体由柔性管“连接”的直接结果，这些柔性管响应心脏泵送的血液而膨胀和收缩。当我们年轻的时候，我们的血管非常有弹性和“顺应性”。随着年龄的增长，它们会自然变硬，如果我们过着不健康和不活跃的生活方式，“动脉硬化”可能会危及生命。糖尿病是西方世界最常见的疾病之一，它与“血管顺应性”的丧失有关。因此，能够测量体内所有重要血管的顺应性具有重大的医学价值。如果能够测量血管内的压力，则可以相当容易地确定顺应性。在这种情况下，人们可以测量由已知的压力增加引起的血管直径的增加。这对于从体内移除的血管效果很好，但很难应用于活体受试者。因此，生理学家开发了另一种方法：测量脉搏离开心脏的速度。众所周知，声音在钢铁等固体中的传播速度比在空气中快得多。这是因为钢的可压缩性比空气小得多。因此，声速是固体介质弹性特性的直接测量。血管也是如此，如果血管僵硬，则它们从心脏传输动脉搏动的速度会比血管顺应时更快。这个想法已成功用于测量体内大血管的顺应性。然而，了解体内最小的血管（即直径为 0.2 毫米或更小的血管）也是非常有趣的。这些血管形成微循环，并执行将氧气和其他营养物质实际输送到需要它们的细胞的重要功能。在此应用中，我们希望探索一种测量此类小型血管弹性特性的新概念。我们将应用一种新技术，一种光学雷达，以前所未有的分辨率（几千毫米）对这些血管中的血流进行成像。通过仔细测量动脉脉搏期间流速和血管直径如何一起变化，应该可以首次确定活体受试者中这些血管的弹性特性。在这项初步研究中，我们希望在一个简单的理想化系统中测试这个想法的基础；如果鼓励试点数据将为更全面的调查奠定基础。我们以这种方式收集的信息在很多方面都很重要。例如，在糖尿病中，血管顺应性的丧失会导致充血反应的丧失，通常情况下，身体会通过增加新鲜血液的爆发来应对暂时的血流丧失。然而，目前尚不清楚血管顺应性的变化是否是此类疾病的原因或影响。众所周知，糖尿病患者必须忍受一系列非常不愉快的症状，其根本原因与微循环扰乱细胞血液供应的概念非常吻合。当足部神经死亡，导致感觉缺失和相关的疼痛性压疮爆发时，就会出现糖尿病足的情况。糖尿病视网膜病变是由于视网膜中对光做出反应的神经死亡而导致的逐渐失明。我们的研究项目是光学物理学家、流体动力学家和微血管生理学家之间的联合合作。它的目的是应用尖端的光学物理和流体流动模型来提高我们对微循环疾病的理解。最终，这可能会导致开发出更好的药物来控制微血管疾病的症状，从而改善数百万患者的生活质量。