Health Telematics Science Institute, Kaunas University of Technology, Kaunas, Lithuania.
Department of Neurology, Academy of Medicine, Lithuanian University of Health Sciences, Kaunas, Lithuania.
Neurocrit Care. 2019 Feb;30(1):42-50. doi: 10.1007/s12028-018-0569-x.
This prospective study of an innovative non-invasive ultrasonic cerebrovascular autoregulation (CA) monitoring method is based on real-time measurements of intracranial blood volume (IBV) reactions following changes in arterial blood pressure. In this study, we aimed to determine the clinical applicability of a non-invasive CA monitoring method by performing a prospective comparative clinical study of simultaneous invasive and non-invasive CA monitoring on intensive care patients.
CA was monitored in 61 patients with severe traumatic brain injuries invasively by calculating the pressure reactivity index (PRx) and non-invasively by calculating the volumetric reactivity index (VRx) simultaneously. The PRx was calculated as a moving correlation coefficient between intracranial pressure and arterial blood pressure slow waves. The VRx was calculated as a moving correlation coefficient between arterial blood pressure and non-invasively-measured IBV slow waves.
A linear regression between VRx and PRx averaged per patients' monitoring session showed a significant correlation (r = 0.843, p < 0.001; 95% confidence interval 0.751 - 0.903). The standard deviation of the difference between VRx and PRx was 0.192; bias was - 0.065.
This prospective clinical study of the non-invasive ultrasonic volumetric reactivity index VRx monitoring, based on ultrasonic time-of-flight measurements of IBV dynamics, showed significant coincidence of non-invasive VRx index with invasive PRx index. The ultrasonic time-of-flight method reflects blood volume changes inside the acoustic path, which crosses both hemispheres of the brain. This method does not reflect locally and invasively-recorded intracranial pressure slow waves, but the autoregulatory reactions of both hemispheres of the brain. Therefore, VRx can be used as a non-invasive cerebrovascular autoregulation index in the same way as PRx and can also provide information about the CA status encompassing all intracranial hemodynamics.
本前瞻性研究创新性的非侵入性超声脑血管自动调节（CA）监测方法，基于颅内血容量（IBV）对动脉血压变化的实时反应测量。在这项研究中，我们旨在通过对重症监护患者进行同时的侵入性和非侵入性 CA 监测的前瞻性对比临床研究，确定非侵入性 CA 监测方法的临床适用性。
通过计算压力反应指数（PRx）对 61 例严重创伤性脑损伤患者进行 CA 监测，同时通过计算容积反应指数（VRx）进行非侵入性监测。PRx 通过颅内压与动脉血压慢波之间的移动相关系数计算得出。VRx 通过动脉血压与非侵入性测量的 IBV 慢波之间的移动相关系数计算得出。
根据患者监测会话的平均值进行 VRx 和 PRx 的线性回归显示出显著相关性（r=0.843，p<0.001；95%置信区间为 0.751-0.903）。VRx 和 PRx 之间的差异标准差为 0.192；偏差为-0.065。
这项基于超声飞行时间测量 IBV 动力学的非侵入性超声容积反应指数 VRx 监测的前瞻性临床研究表明，非侵入性 VRx 指数与侵入性 PRx 指数具有显著一致性。超声飞行时间法反映了声路内的血液体积变化，声路穿过大脑的两个半球。该方法不反映局部和侵入性记录的颅内压力慢波，但反映了大脑两个半球的自动调节反应。因此，VRx 可以像 PRx 一样用作非侵入性脑血管自动调节指数，还可以提供有关涵盖所有颅内血流动力学的 CA 状态的信息。
