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

Abstract

Background Intracranial pressure (ICP) monitoring requires placing a hole in the skull through which an invasive pressure monitor is inserted into the brain. This approach has risks for the patient and is expensive. We have developed a non-invasive brain pulse monitor that uses red light to detect a photoplethysmographic (PPG) signal arising from the blood vessels on the brain’s cortical surface. The brain PPG and the invasive ICP waveform share morphological features which may allow measurement of the intracranial pressure. Methods We enrolled critically ill patients with an acute brain injury with invasive ICP monitoring to assess the new monitor. A total of 24 simultaneous invasive ICP and brain pulse monitor PPG measurements were undertaken in 12 patients over a range of ICP levels. Results The waveform morphologies were similar for the invasive ICP and brain pulse monitor PPG approach. Both methods demonstrated a progressive increase in the amplitude of P2 relative to P1 with increasing ICP levels. An automated algorithm was developed to assess the PPG morphological features in relation to the ICP level. A correlation was demonstrated between the brain pulse waveform morphology and ICP levels, R 2 =0.66, P < 0.001. Conclusion The brain pulse monitor’s PPG waveform demonstrated morphological features were similar to the invasive ICP waveform over a range of ICP levels, these features may provide a method to measure ICP levels. Trial Registration ACTRN12620000828921.

Cerebrovascular Responses in a Patient with Lundberg B Waves Following Subarachnoid Haemorrhage Assessed with a Novel Non-Invasive Brain Pulse Monitor: A Case Report

“…The monitor has been described in detail previously. [22][23][24] In brief, the monitor uses near-infrared (NIR) light sources (660 and 940 nm). Each brain sensor has a single light-emitting diode (LED) and photodetector (PD).…”

“…[28][29][30][31] The PPG signal is feature-rich and allows estimation of blood flow, ICP, compliance and oxygen saturation. [22][23][24] Invasive ICP An extra-ventricular drain was placed in the right lateral ventricle. The pressure levels were zeroed at the tragus and monitored by a Philips IntelliVue system.…”

“…The PPG signal provides information on intracranial pressure (ICP), compliance, blood flow and tissue oxygen saturation (StO 2 ). [22][23][24] Here we present a case demonstrating the monitor's ability to detect variations in the brain photoplethysmography (PPG) signal indicative of intracranial pressure fluctuations, compliance alterations, blood flow changes and tissue oxygen saturation (StO 2 ) in realtime, and non-invasively.…”

A Point-of-Care Noninvasive Technique for Surrogate ICP Waveforms Application in Neurocritical Care

“…However, they found only a fair estimation of the ICP waveform in a third of their sample and did not recommend its use for clinical management [ 27 ]. More recently, Dixon et al [ 28 ] developed an algorithm using photoplethysmography to assess the correlation between morphological features of the photoplethysmography waveform and ICP levels. This study involved 24 simultaneous recordings in 12 patients with ABI without skin or skull injuries.…”

“…The authors observed a significant correlation between the morphology of the brain pulse wave and ICP levels ( R 2 = 0.66, p = 0.001). However, further validation studies with larger and preferably blinded samples are needed to confirm these findings [ 28 ].…”