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, R²=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.

Keywords:

• intracranial pressure
• acute brain injury
• monitoring
• non-invasive
• photoplethysmography

Data Sharing Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Acknowledgments

We would like to acknowledge Robert Tran from Keylead Health for his contributions to the algorithm development.

Author Contributions

All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work. Specific contributions included but were not limited to the following. B.D conceived the study. B.D., J.D.S., A.U. and P.S. designed the human study protocol. B.D and J.S.S developed the sensor hub. B.D., J.S., and E.J.T collected data. B.D., J.S., S.A.G. J.H and E.J.T analyzed the data and interpreted the results. B.D. wrote the first manuscript draft.

Disclosure

BD is the founder and Chief Scientific Officer of Cyban, Pty Ltd and reports grants, personal fees from Cyban, during the conduct of the study; In addition, Dr Barry Dixon has patents US9717446B2 and WO2008134813A1 issued to Cyban. J.M.S., S.A.G., E.J.T., J.H and J.S.S. are paid employees of Cyban. The hospital departments of J.D.S, and A.U. received financial support from Cyban to undertake the study. A.U. reports non-financial support from Integra Lifesciences, outside the submitted work. The remaining author, P.S., has no conflicts of interest to declare for this work.

Additional information

Funding

The research was supported by a grant from the Biomedtech Horizons Program part of the Medical Research Future Fund of the Australian Government.