Intracranial pressure monitoring by time domain analysis.

This paper discusses the developments in the assessment of intracranial hypertension in humans and recent research carried out by the authors on the techniques for the non-invasive measurement of intracranial pressure. A brief historical review sets the scene with regard to clinical and invasive methods for the observation of intracranial pressure and goes on to look at non-invasive techniques for measuring blood flow and pressure from which it is proposed that intracranial pressure can be predicted. Although a simulation and a frequency domain analysis of the dynamics of the human brain has been carried out, this paper concentrates only on the time domain experiments and analysis. The time domain analysis uses the cross-correlation of the non-invasive blood flow of the middle cerebral artery with blood pressure measurements and their varying phase shift with trauma characteristics to make predictions of intracranial pressure trends that lead to pathologically dangerous conditions. The paper concludes with a section concerning the development of software and associated graphical displays that could inform staff of trends in intracranial pressure and life threatening conditions so that immediate action can be taken.