Novel Method and Device for Fully Non-Invasive Cerebrovascular Autoregulation Monitoring

Comparative Study of Novel Noninvasive Cerebral Autoregulation Volumetric Reactivity Indices Reflected by Ultrasonic Speed and Attenuation as Dynamic Measurements in the Human Brain

“…CA status was monitored using a novel noninvasive ultrasonic monitor developed by the Health Telematics Science Institute at the Kaunas University of Technology (Kaunas, Lithuania) for real-time monitoring of ultrasound speed and attenuation dynamics in the human brain. The technology provides real-time information regarding IBV changes and waves in the cerebral vessels responsible for CA [29][30][31]. Such changes and waves are causes of intracranial pressure (ICP(t)) changes and waves [32].…”

“…In new noninvasive technology, ICP(t) slow waves, was replaced by IBV(t) slow waves, and CA status was estimated by calculating the noninvasive VRx(t) as a moving correlation coefficient between the slow waves of IBV(t) and ABP(t). Slow ABP(t) and IBV(t) B waves with a period of 0.5-2.0 min reflected the vasogenic activity of cerebrovascular autoregulation and were used for VRx(t) calculations [29][30][31]38]. A head frame including a pair of ultrasonic transducers on either side of the head was positioned so that the acoustic path crossed intracranial media, including parenchyma and brain ventricles, but avoiding large arteries and veins.…”

“…The ABP(t) slow wave reference signal was taken from a noninvasive ABP(t) Finapres Nova monitor. Negative values of both VRx(t) < 0 corresponded to intact CA status, and positive VRx(t) values > indicated CA impairment [15,28,29,[33][34][35][36][37]. Two-minute moving averages of both VRx(t) were used to obtain a temporal resolution of CA impairments that were at least two times better than those obtained with NIRS or Doppler CA monitors.…”

“…Another comparative study with 11 patients with brain injuries revealed a significant relationship associated with VRx and PRx outcomes [29], which indicated that VRx reflects autoregulation the same as PRx. Additionally, the applicability of the noninvasive IBV monitoring technique for cerebrovascular autoregulation monitoring has reflected the similarity between invasive ICP and noninvasive IBV [29][30][31], which are used to derive the reactivity indices (PRx, VRx). In this study, we investigated novel noninvasive ultrasonic methods developed by the Health Telematics Science Institute at the Kaunas University of Technology (Kaunas, Lithuania) based on real-time monitoring of ultrasound speed and compared that with attenuation dynamics.…”

“…Clinical applicability of the VRx has been proven by several clinical studies conducted by the Health Telematics Science Institute at the Kaunas University of Technology (Kaunas, Lithuania), such as the noninvasive ultrasonic VRx based on time-of-flight measurements with the invasive PRx on 61 patients with brain injuries and showed excellent coincidence to reflect autoregulation [25]. Another comparative study with 11 patients with brain injuries revealed a significant relationship associated with VRx and PRx outcomes [29], which indicated that VRx reflects autoregulation the same as PRx. Additionally, the applicability of the noninvasive IBV monitoring technique for cerebrovascular autoregulation monitoring has reflected the similarity between invasive ICP and noninvasive IBV [29][30][31], which are used to derive the reactivity indices (PRx, VRx).…”