Non-invasive Estimation of the Intracranial Pressure Waveform from the Central Arterial Blood Pressure Waveform in Idiopathic Normal Pressure Hydrocephalus Patients

Karen Brastad Evensen,Fabrice Prieur,Per Kristian Eide,Sverre Holm,Michael O’Rourke

doi:10.1038/s41598-018-23142-7

Karen Brastad Evensen, Fabrice Prieur + Show 3 more

Open Access

https://doi.org/10.1038/s41598-018-23142-7

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Abstract

This study explored the hypothesis that the central aortic blood pressure (BP) waveform may be used for non-invasive estimation of the intracranial pressure (ICP) waveform. Simultaneous invasive ICP and radial artery BP waveforms were measured in 29 individuals with idiopathic normal pressure hydrocephalus (iNPH). The central aortic BP waveforms were estimated from the radial artery BP waveforms using the SphygmoCor system. For each individual, a transfer function estimate between the central aortic BP and the invasive ICP waveforms was found (Intra-patient approach). Thereafter, the transfer function estimate that gave the best fit was chosen and applied to the other individuals (Inter-patient approach). To validate the results, ICP waveform parameters were calculated for the estimates and the measured golden standard. For the Intra-patient approach, the mean absolute difference in invasive versus non-invasive mean ICP wave amplitude was 1.9 ± 1.0 mmHg among the 29 individuals. Correspondingly, the Inter-patient approach resulted in a mean absolute difference of 1.6 ± 1.0 mmHg for the 29 individuals. This method gave a fairly good estimate of the wave for about a third of the individuals, but the variability is quite large. This approach is therefore not a reliable method for use in clinical patient management.

Highlights

One approach for non-invasive intracranial pressure (ICP) monitoring has been to estimate ICP from radial artery blood pressure (BP) measurements, either solely based on radial artery BP, or in conjunction with blood velocity measurements[11,12,13]
This was supported by a previously conducted preliminary study that reported that the central aortic BP waveform compared better with the ICP waveform than the radial artery BP retrieved from radial artery measurements[14]
The authors reported that the central aortic BP waveform was almost identical to the ICP waveform during the period of systole, and that the augmentation index was similar to that of ICP

Summary

Introduction

One approach for non-invasive ICP monitoring has been to estimate ICP from radial artery blood pressure (BP) measurements, either solely based on radial artery BP, or in conjunction with blood velocity measurements[11,12,13] This is an appealing approach as radial artery BP is routinely measured in clinical setting. The first approach was to generate a transfer function estimate from the central aortic BP waveform to the invasive ICP waveform for each patient This was done to investigate the potential of the method. The second approach was to utilize the transfer function estimate from the Intra-patient approach that gave the highest cross correlation between the non-invasive ICP estimate and the invasively measured ICP waveforms on the total cohort of individuals. The first approach provides important information about the possibility of using the central aortic BP waveforms as a source for non-invasive ICP estimation, while the second approach has potential clinical value

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Conclusion