Sorond Farzaneh A, Serrador Jorge M, Jones Richard N, Shaffer Michele L, Lipsitz Lewis A
Department of Neurology, Stroke Division, Brigham and Women's Hospital, Boston, MA 02115, USA.
Ultrasound Med Biol. 2009 Jan;35(1):21-9. doi: 10.1016/j.ultrasmedbio.2008.08.001. Epub 2008 Oct 2.
Measurement of cerebral autoregulation is important for the evaluation and management of a number of clinical disorders that affect cerebral blood flow. We currently lack simple bedside measures that mimic common physiologic stresses. Therefore, we evaluated a new sit-to-stand technique as an alternative method to the frequently-used thigh-cuff technique in healthy volunteers. Continuous middle cerebral artery (MCA) blood flow velocities (BFV) and arterial blood pressure (ABP) were measured in response to standing from a sitting position, or rapid thigh-cuff deflation in 24 healthy subjects (50 +/- 22 y). Autoregulatory index (ARI) was calculated as the BFV response for step changes in ABP using a second-order differential equation with a set of parameters that can be used to grade the performance of autoregulation. Of these 24 subjects, 30% could tolerate only two thigh-cuffs and refused to proceed with the third cuff, whereas none of our subjects had any difficulty with performing the three sit-to-stand trials. The two techniques produced similar changes in mean ABP, but the times to nadir of the blood pressure and BFV were significantly faster for the thigh-cuff. The mean group ARIs were similar between the two techniques. Although between-subjects variability was higher for sit-to-stand ARIs, the within-subject sit-to-stand ARI variability was small. Thus, for the assessment of cerebral autoregulation, the sit-to-stand procedure is well tolerated and produces ARI values that have low within-subject variability. The sit-to-stand technique appears to be a suitable measure of individual ARI values for inferring dynamic cerebral autoregulation.
脑自动调节功能的测量对于评估和管理多种影响脑血流量的临床疾病至关重要。目前，我们缺乏能模拟常见生理应激的简单床边测量方法。因此，我们在健康志愿者中评估了一种新的从坐到站的技术，作为常用的大腿袖带技术的替代方法。在24名健康受试者（50±22岁）中，测量了他们从坐姿站立或快速放气大腿袖带时大脑中动脉（MCA）的连续血流速度（BFV）和动脉血压（ABP）。使用二阶微分方程和一组可用于评估自动调节功能的参数，将自动调节指数（ARI）计算为ABP阶跃变化时的BFV反应。在这24名受试者中，30%的人只能耐受两个大腿袖带，拒绝进行第三个袖带的测量，而我们的受试者在进行三次从坐到站的试验时均没有困难。两种技术使平均ABP产生的变化相似，但大腿袖带测量时血压和BFV达到最低点的时间明显更快。两种技术的平均组ARI相似。虽然从坐到站的ARI在受试者之间的变异性较高，但受试者内从坐到站的ARI变异性较小。因此，对于脑自动调节功能的评估，从坐到站的程序耐受性良好，且产生的ARI值在受试者内变异性较低。从坐到站的技术似乎是一种适用于推断动态脑自动调节功能的个体ARI值的测量方法。
