Validity of cerebral arterial blood flow calculations from velocity measurements.
Validity of cerebral arterial blood flow calculations from velocity measurements.
复制标题
根据速度测量计算脑动脉血流量的有效性。
作者：
Kontos,HA
显然，能够连续测量通过脑动脉的血流量的无创技术对于临床和研究目的非常有价值。开发这种技术最有前途的方法是使用超声波来测量血流速度。由于通过血管的血流量等于瞬时平均速度乘以血管的横截面积，因此速度和血管口径的监测提供了估计血流量所需的基本测量值。 Busija 等人表明这种方法既准确又有用。他们用放置在动脉周围的超声波多普勒探头测量了猫和狗脑动脉的血流速度，同时通过直接可视化测量了血管直径。他们发现，根据速度和血管口径计算出的血流与直接用放射性微球测量的血流密切相关。在本期《中风》中，阿斯利德和他的同事2测量了人类志愿者大脑中动脉的血流速度，以研究脑血流对动脉血压快速下降的反应。这些作者开发的方法涉及某些重要假设，这些假设可能对结果的有效性产生关键影响。 1 检查这些假设的合理性及其对技术有用性的潜在影响。应牢记 Aaslid 等人使用的方法的两个重要特征。首先，这些作者没有测量血管口径，他们假设大脑中动脉在他们使用的干预措施中具有恒定的横截面积。其次，他们没有测量通过大脑中动脉的平均速度，而是测量最大速度。作者证明了他们关于容器口径不变的假设
It is obvious that a noninvasive technique that can provide continuous measurements of blood flow through a cerebral artery would be very valuable for clinical and investigative purposes. The most promising approach to the development of such a technique involves the use of ultrasound for the measurement of blood flow velocity. Since blood flow through a vessel is equal to the instantaneous average velocity times the cross-sectional area of the vessel, monitoring of velocity and vessel caliber provides the essential measurements that are needed to estimate blood flow. Busija et al1 showed that such a method is both accurate and useful. They measured blood flow velocity in a cerebral artery in cats and dogs with an ultrasonic Doppler probe placed around the artery, and simultaneously they measured vessel diameter by direct visualization. They found that blood flow calculated from the velocity and vessel caliber correlated exceedingly well with blood flow measured directly with radioactive microspheres. In this issue of Stroke, Aaslid and his colleagues2 measured blood flow velocity in the middle cerebral artery of human volunteers to investigate the responses of cerebral blood flow to rapid decreases in arterial blood pressure. The approach developed by these authors involves certain important assumptions that can have a critical influence on the validity of the results. 1 examine the soundness of these assumptions and their potential consequences on the usefulness of the technique. Two important features of the method used by Aaslid et al2 should be borne in mind. First, these authors did not measure vessel caliber, and they assumed that the middle cerebral artery had a constant cross-sectional area throughout the interventions they used. Second, they did not measure average velocity through the middle cerebral artery but maximum velocity. The authors justified their assumption of an unchanging vessel caliber in the