Realization of a Comprehensive Non-invasive Detection of Intracranial Pressure Analyzer Based upon FVEP and TCD
Up to now, several methods, such as flash visual evoked potential (FVEP) and transcranial Doppler (TCD), have been studied with regard to assessing intracranial pressure (ICP) non-invasively. However, there are still no instruments that are readily availa
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Abstract Up to now, several methods, such as flash visual evoked potential (FVEP) and transcranial Doppler (TCD), have been studied with regard to assessing intracranial pressure (ICP) non-invasively. However, there are still no instruments that are readily available for non-invasive measurement of ICP in clinical practice. Based on the advantages of FVEP and TCD for ICP assessment, the two methods are synthesized to develop a specific instrument to non-invasively measure ICP more reliably and applicably, as the integration of FVEP and TCD overcomes the shortcomings of a single method of ICP measurement. Keywords Intracranial pressure (ICP) • Flash visual evoked potential (FVEP) • Transcranial Doppler (TCD) • Instrument • Non-invasive detection
Materials and Methods FVEP The basis of the FVEP being used to detect ICP non-invasively is the positive correlation between the latency of the N2 wave and ICP. Currently, the correlation relation is generally believed to be linearity [5, 9]. However, there is a comparatively large error in the high intracranial pressure segment in our clinical experiments. Further study shows that the correlation relation in the high pressure segment could be revised to be a power relation, which reflects the change in ICP more accurately. It can be expressed as nICP = a × t b + c , where t is the latency of the N2 wave, a is an adjustment coefficient, b is the exponentiation, and c is a constant.
Background TCD Method Non-invasive methods of intracranial pressure (ICP) measurement, such as flash visual evoked potential (FVEP) and transcranial Doppler (TCD), have been studied a great deal in the literature [2, 6, 7]. However, owing to the limitations of these methods in the non-invasive detection of ICP, they have not been routinely used in clinical practice. In this paper, FVEP and TCD are synthetically applied in a sameinstrument platform using virtual instrument technology. In this way, the applicability and precision of the non-invasive detection of ICP will be improved.
J.I. Zhong () and Y. Li College of Bioengineering, Chongqing University, Chongqing 400030, China e-mail: [email protected] X. Minhui and Z. Yihua Department of Neurosurgery, Daping Hospital, the Third Military Medical University, Chongqing 400042, China
The literature shows that the hemodynamic parameters, such as the pulsatility index (PI), resistance index (RI), systolic peak flow velocity (Vs), end-diastolic flow velocity (Vd), and mean flow velocity (Vm) are related to intracranial hypertension [1, 8]. Nevertheless, the real-time dynamic variation of ICP cannot yet be monitored by TCD. Some scholars have achieved the continuous monitoring of ICP changes by using arterial blood pressure (ABP), cerebral blood flow velocity (CBFV), and ICP in the nonlinear mapping function [3, 4]. In this paper, the hemodynamic parameters were obtained by recording and analyzing the audio signal from the TCD instrument, and computing the ICP value with the nonlinear model between hemodynamic parameters and ICP.
Instrument Realiz
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