Clinical translation of noninvasive intracranial pressure sensing with diffuse correlation spectroscopy

Abstract

OBJECTIVE Intracranial pressure (ICP) is an important therapeutic target in many critical neuropathologies. The current tools for ICP measurements are invasive; hence, these are only selectively applied in critical cases where the benefits surpass the risks. To address the need for low-risk ICP monitoring, the authors developed a noninvasive alternative. METHODS The authors recently demonstrated noninvasive quantification of ICP in an animal model by using morphological analysis of microvascular cerebral blood flow (CBF) measured with diffuse correlation spectroscopy (DCS). The current prospective observational study expanded on this preclinical study by translating the method to pediatric patients. Here, the CBF features, along with mean arterial pressure (MAP) and heart rate (HR) data, were used to build a random decision forest, machine learning model for estimation of ICP; the results of this model were compared with those of invasive monitoring. RESULTS Fifteen patients (mean age ± SD [range] 9.8 ± 5.1 [0.3–17.5] years; median age [interquartile range] 11 [7.4] years; 10 males and 5 females) who underwent invasive neuromonitoring for any purpose were enrolled. Estimated ICP (ICPest) very closely matched invasive ICP (ICPinv), with a root mean square error (RMSE) of 1.01 mm Hg and 95% limit of agreement of ≤ 1.99 mm Hg for ICPinv 0.01–41.25 mm Hg. When the ICP range (ICPinv 0.01–29.05 mm Hg) was narrowed on the basis of the sample population, both RMSE and limit of agreement improved to 0.81 mm Hg and ≤ 1.6 mm Hg, respectively. In addition, 0.3% of the test samples for ICPinv ≤ 20 mm Hg and 5.4% of the test samples for ICPinv > 20 mm Hg had a limit of agreement > 5 mm Hg, which may be considered the acceptable limit of agreement for clinical validity of ICP sensing. For the narrower case, 0.1% of test samples for ICPinv ≤ 20 mm Hg and 1.1% of the test samples for ICPinv > 20 mm Hg had a limit of agreement > 5 mm Hg. Although the CBF features were crucial, the best prediction accuracy was achieved when these features were combined with MAP and HR data. Lastly, preliminary leave-one-out analysis showed model accuracy with an RMSE of 6 mm Hg and limit of agreement of ≤ 7 mm Hg. CONCLUSIONS The authors have shown that DCS may enable ICP monitoring with additional clinical validation. The lower risk of such monitoring would allow ICP to be estimated for a wide spectrum of indications, thereby both reducing the use of invasive monitors and increasing the types of patients who may benefit from ICP-directed therapies.

Pulsatile microvascular cerebral blood flow waveforms change with intracranial compliance and age

“…These devices are noninvasive and easy to use, making them an attractive option for clinical applications. [1][2][3][4] The use of DCS in clinical settings has been explored for various applications, such as predicting intracranial pressure (ICP), [5][6][7] measuring dynamic cerebral autoregulation in stroke patients, 8 monitoring intraventricular hemorrhage vulnerability in newborns, 9 and estimating critical closing pressure (CrCP). 10,11 Currently, transcranial doppler ultrasound (TCD) is the gold-standard method to measure the cerebral blood flow velocity (CBFV) in the large arteries of the brain.…”

“…Recent work has investigated using pulsatile rCBF waveforms measured with DCS as potential biomarkers for ICP and CrCP in clinical settings. [5][6][7]10,11 However, there are limited studies quantifying what factors impact the morphological features of DCS pulsatile waveforms. 15 It is believed that the rCBF waveforms measured have distinct characteristics from pulsatile blood flow waveforms in the periphery due to their confinement by a rigid skull.…”

“…12,32 Finally, the AUC has been shown to be an important feature when predicting ICP noninvasively with pulsatile DCS waveforms. 5,6 Here we examine how these three features change in patients with CM and with vascular stiffness driven by normal aging.…”

Assessment of a Non-Invasive Brain Pulse Monitor to Measure Intra-Cranial Pressure Following Acute Brain Injury

“… 22–26 A relationship with ICP levels was demonstrated in some studies, but the algorithms also included other variables known to correlate with ICP, such as blood pressure. 22 , 23 The contribution of the scalp tissues blood flow to the signal may also be a limitation. 22 , 26–28 To date these approaches remain at a research stage.…”

Can diffuse reflectance spectroscopy identify shuntodynia in pediatric hydrocephalus patients?

“…Optical spectroscopic methods have also been widely used to monitor and assess pain in exercise science and sports-medicine [16][17][18][19] . Parallelly, a related diffuse optical technique called diffusion correlation spectroscopy (DCS) has been used in pediatric subjects with hydrocephalus for rapid and non-invasive assessment of intracranial pressure (ICP) [20][21][22][23][24] . However, to the best of our knowledge optical sensing has not been applied or explored in the realm of shuntodynia this far.…”