City Research Online

In Vitro Evaluation of a Non-Invasive Photoplethysmography Based Intracranial Pressure Sensor

Abay, T. Y. Y., Phillips, J. P. P., Uff, C. , Roldan, M. & Kyriacou, P. A. ORCID: 0000-0002-2868-485X (2022). In Vitro Evaluation of a Non-Invasive Photoplethysmography Based Intracranial Pressure Sensor. Applied Sciences, 13(1), 534. doi: 10.3390/app13010534


Intracranial pressure (ICP) is an important measurement in the treatment of Traumatic Brain Injury (TBI). Currently, ICP can only be measured invasively, which exposes patients to operative risk and can only be performed by neurosurgeons. Hence, there is a significant need for a non-invasive ICP technology. This paper describes the evaluation of a novel non-invasive intracranial pressure (nICP) monitor which uses the Photoplethysmogram (PPG) to measure the ICP. The monitor was evaluated in an in vitro model that simulated cerebral haemodynamics and allowed the controlled manipulation of ICP. A number of features from the PPG were extracted and utilised in a machine learning model to estimate ICP. Three separate measurements in which the ICP was varied were performed, and the estimated ICP (nICP) was compared with reference (invasive) ICP measurements. The ICP estimated by the nICP monitor was highly correlated with reference ICP measurements (Pearson’s correlation coefficient between 0.95 and 0.98). The nICP monitor also showed a low Root Mean Square Error from the reference ICP measure (3.12, 1.48, and 1.45 mmHg). Analysis of agreement by Bland and Altman also revealed good agreement between the two techniques. The optical nICP monitor was able to estimate the ICP non-invasively from an in vitro model simulating intracranial hypertension. The non-invasive ICP monitor showed very promising results which can set the base for further investigations. This work contributes significantly to the quest for non-invasive ICP monitoring in Traumatic Brain Injury (TBI), and paves the way for further research in this field.

Publication Type: Article
Additional Information: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (
Publisher Keywords: optical phantom; non-invasive monitoring; intracranial pressure monitoring; traumatic brain injury; photoplethysmography (PPG); near-infrared sensing; machine learning modelling
Subjects: R Medicine > RC Internal medicine
Departments: School of Science & Technology > Engineering
[thumbnail of applsci-13-00534-v2.pdf]
Text - Published Version
Available under License Creative Commons Attribution.

Download (2MB) | Preview


Add to AnyAdd to TwitterAdd to FacebookAdd to LinkedinAdd to PinterestAdd to Email


Downloads per month over past year

View more statistics

Actions (login required)

Admin Login Admin Login