Pseudo-Bayesian Model-Based Noninvasive Intracranial Pressure Estimation and Tracking

Abstract

A noninvasive intracranial pressure (ICP) estimation method is proposed that incorporates a model-based approach within a probabilistic framework to mitigate the effects of data and modeling uncertainties. Methods: A first-order model of the cerebral vasculature relates measured arterial blood pressure (ABP) and cerebral blood flow velocity (CBFV) to ICP. The model is driven by the ABP waveform and is solved for a range of mean ICP values to predict the CBFV waveform. The resulting errors between measured and predicted CBFV are transformed into likelihoods for each candidate ICP in two steps. First, a baseline ICP estimate is established over five data windows of 20 beats by combining the likelihoods with a prior distribution of the ICP to yield an a posteriori distribution whose median is taken as the baseline ICP estimate. A single-state model of cerebral autoregulatory dynamics is then employed in subsequent data windows to track changes in the baseline by combining ICP estimates obtained with a uniform prior belief and model-predicted ICP. For each data window, the estimated model parameters are also used to determine the ICP pulse pressure. Results: On a dataset of thirteen pediatric patients with a variety of pathological conditions requiring invasive ICP monitoring, the method yielded for mean ICP estimation a bias (mean error) of 0.6 mmHg and a root-mean-squared error of 3.7 mmHg. Conclusion: These performance characteristics are well within the acceptable range for clinical decision making. Significance:

A Spectral Approach to Model-Based Noninvasive Intracranial Pressure Estimation

“…Noninvasive assessment of brain health remains one of the pressing open challenges in clinical neuroscience. To address this need, a series of model-based approaches to noninvasive and continuous ICP estimation have recently been proposed based on the analysis of time-locked measurements of CBFV and (peripheral) ABP waveform measurements [23]- [30]. Some of these approaches rely on reduced-order models of the cerebrospinal physiology [23]- [26], [28]- [30] while others represent the relevant anatomy and physiological relationships in more detail [27].…”

“…To address this need, a series of model-based approaches to noninvasive and continuous ICP estimation have recently been proposed based on the analysis of time-locked measurements of CBFV and (peripheral) ABP waveform measurements [23]- [30]. Some of these approaches rely on reduced-order models of the cerebrospinal physiology [23]- [26], [28]- [30] while others represent the relevant anatomy and physiological relationships in more detail [27]. The majority of prior work has approached the estimation problem in the time domain, which requires consideration of how to align the waveform measurements and thereby overcome temporal offsets inherent in measuring physiological waveforms with different medical devices and at different anatomical locations.…”

“…In the past, most approaches that infer ICP from CBFV and ABP waveform recordings have largely focused on learningbased or data-driven methods [19], [21]. More recently, modelbased methods have been developed that leverage our mechanistic understanding of the underlying physiology to estimate ICP in a model-based manner [22]- [30]. These model-based methods analyze the ABP and CBFV waveform measurements in the context of mechanistic models of the relevant cerebrospinal physiology.…”

“…These model-based methods analyze the ABP and CBFV waveform measurements in the context of mechanistic models of the relevant cerebrospinal physiology. While such noninvasive ICP estimation has traditionally focused on estimating the mean ICP value, it has been suggested that the ICP pulse pressure or waveform morphology carry important diagnostic and prognostic information [31]- [33], and hence ICP pulse pressure or full waveform estimation has recently become the focus of attention as well [27], [30].…”

Review: pathophysiology of intracranial hypertension and noninvasive intracranial pressure monitoring

“…Due to the somewhat complicated interplay between ICP, arterial pressure, and cerebral hemodynamics, a large number of methods have attempted to incorporate arterial pressure measurements, which may provide complementary information to assist in measuring ICP [125,154,155,[157][158][159][160][161][162][163][169][170][171][172][173][174][175]. These methods are not technically noninvasive as they require the placement of a radial artery catheter for monitoring ABP; however, this procedure is typically already performed as part of standard care in neurointesive care units, and the risks associated with monitoring ABP via radial artery catheter are considered significantly less risky than invasive ICP monitoring.…”