Non-Invasive Carotid Artery Measurements for Continuous Intracranial Pressure Monitoring

PROJECT SUMMARY
Continuous intracranial pressure (ICP) monitoring is an important surveillance tool for critically ill neurologic
patients that provides
critical insights on disease severity for guiding medical management
. However,
ICP
monitoring requires a highly invasive procedures that incurs risks for intracranial hemorrhage and infection.24–28
Thus, the clinical indications for ICP monitoring are a topic of debate and up to 50% of traumatic brain injury
patients who fulfill recommendation criteria for an ICP monitor never receive it.22 Moreover, nearly half of patients
admitted to the Neuro-Intensive Care Unit (Neuro-ICU) without an ICP monitor go on to later develop elevated
ICP.1 Unfortunately, even eligible patients are only provided ICP monitoring while in the Neuro-ICU. After
adequate recovery, they are transferred to a step-down unit without a monitor even though they are still at high
risk for developing elevated ICPs and potentially fatal brain herniation. Therefore, there is a clear unmet need
for a non-invasive approach to continuous ICP monitoring.
We propose to develop a non-invasive sensing system to continuously monitor ICP by correlating beat-
to-beat carotid artery BP to ICP.
Prior studies have demonstrated that central aortic waveforms detected at
the extracranial portion of the carotid artery closely resemble ICP waveforms.3-10 In our previous work, we
developed highly sensitivity conformal sensors capable of measuring carotid artery BP waveforms with minimal
applanation pressure.
36,37 W
e have also demonstrated a novel pressure estimation algorithm that can sustain
high accuracy radial artery BP measurements in surgical and ICU patients.
13 By combining our highly sensitive
sensors with our generalizable pressure estimation algorithm,
we hypothesize that we can non-invasively and
continuously monitor ICP by developing a parameter estimation model to correlate our sensor's carotid BP
measurements with ICP waveforms using recordings from Neuro-ICU patients for training and validation
.
Studies
have also demonstrated the clinical utility of other ICP waveform-derived indices for assessing intracranial
compliance and prognosticating patient outcomes.14–18 Due to the morphological similarity between carotid BP
and ICP waveforms, we hypothesize that these waveform features can also be applied to our carotid BP
measurements and sensor-derived ICP estimations to gain unique insights on patient neurologic status that can
aid medical decision-making. T
he findings of this project have the potential to form the basis for future
investigations on utilizing the waveform features of carotid BP as a proxy measure of ICP. Moreover, i
f
successful, our proposed non-invasive, continuous ICP monitor has the potential to not only enhance
neurologic monitoring across a broader range of patients, but also create a paradigm shift in existing
clinical protocols in favor of more proactive ICP surveillance.

Grant Number: 5F30HL167584-04
NIH Institute/Center: NIH
Principal Investigator: Arash Abiri