Watt Brian P, Burnfield Judith M, Truemper Edward J, Buster Thad W, Bashford Gregory R
Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, NE 68583, USA.
Annu Int Conf IEEE Eng Med Biol Soc. 2012;2012:2310-3. doi: 10.1109/EMBC.2012.6346425.
An observational study was performed as a preliminary investigation into the use of transcranial Doppler ultrasound (TCD) for recording cerebral hemodynamic changes during multiple tasks. TCD is a method of measuring cerebral blood flow (CBF) using ultrasound transducers in contact with the surface of the head. Using the maximum flow envelope of the Doppler spectrum returning from the middle cerebral artery (MCA), standard clinical flow indices can be calculated and displayed in real time providing information concerning perturbations in CBF and their potential cause. These indices as well as flow velocity measurements have been recognized as useful in measuring changes in responses to various stimulus that can be used to indicate cardiovascular health. For this study, the pulsatility index (PI) and resistivity index (RI) were chosen since they indicate composite changes indicative of vasoconstriction and vasodilatation which are normal hemodynamic responses under appropriate conditions. A total of eleven participants were recruited to take part in this study. Nine of these individuals had no known disability (Controls); two had experienced unilateral cerebrovascular accidents (Strokes) in the ipsilateral MCA distribution. Maximum velocity envelopes of the spectral Doppler data were recorded using a fixation device designed to stabilize two ultrasound probes (2 MHz) to sample the bilateral MCAs CBF. These measures were performed separately while the subject performed four activities: 1) rest, 2) cognitive challenge, 3) cardiovascular exercise, and 4) simultaneous exercise and cognitive challenge. Cardiovascular parameters were calculated from the data by extracting maximum (Vs) and minimum flow velocities (Vd), PI, RI, and time signatures for each cardiac cycle. The data for all participants shows significant changes in cardiovascular parameters between states of rest and exercise, as well as slight trends across time. Although the data are preliminary, they show the capability of using Doppler spectral examination of the bilateral MCAs in individuals with physical limitation performing cardiovascular exercise. The novelty of examining a population using dynamic exercise who before could not perform such exercise offers the opportunity to study the impact of exercise on global cerebral recovery in unilateral stroke with significant physical impairment.
进行了一项观察性研究，作为对经颅多普勒超声（TCD）在多项任务期间记录脑血流动力学变化的初步调查。TCD是一种使用与头部表面接触的超声换能器测量脑血流量（CBF）的方法。利用从中脑动脉（MCA）返回的多普勒频谱的最大血流包络，可以计算并实时显示标准临床血流指数，提供有关CBF扰动及其潜在原因的信息。这些指数以及血流速度测量已被认为有助于测量对各种刺激的反应变化，可用于指示心血管健康状况。在本研究中，选择了搏动指数（PI）和阻力指数（RI），因为它们指示了血管收缩和血管舒张的综合变化，这是在适当条件下的正常血流动力学反应。总共招募了11名参与者参加本研究。其中9人无已知残疾（对照组）；2人在同侧MCA分布区域经历过单侧脑血管意外（中风）。使用一种固定装置记录频谱多普勒数据的最大速度包络，该装置设计用于稳定两个超声探头（2MHz），以采集双侧MCA的CBF。这些测量在受试者进行四项活动时分别进行：1）休息，2）认知挑战，3）心血管运动，4）同时进行运动和认知挑战。通过提取每个心动周期的最大（Vs）和最小血流速度（Vd）、PI、RI和时间特征，从数据中计算心血管参数。所有参与者的数据显示，休息和运动状态之间心血管参数有显著变化，以及随时间的轻微趋势。尽管数据是初步的，但它们显示了对有身体限制的个体进行心血管运动时使用双侧MCA的多普勒频谱检查的能力。对以前无法进行此类运动的人群进行动态运动检查的新颖之处在于，有机会研究运动对有严重身体损伤的单侧中风患者整体脑恢复的影响。
