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68th Annual Meeting of the German Society of Neurosurgery (DGNC)
7th Joint Meeting with the British Neurosurgical Society (SBNS)

German Society of Neurosurgery (DGNC)

14 - 17 May 2017, Magdeburg

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Computerized ICP Pulse Waveform Analysis: The High Frequency Centroid Revisited

Meeting Abstract

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  • Erhard Lang - Neurosurgical Associates, Red Cross Hospital, Kassel, Deutschland
  • Michal Placek - Department of Biomedical Engineering and Instrumentation, Wroclaw University of Technology, Wroclaw, Poland
  • Magdalena Kasprowicz - Department of Biomedical Engineering and Instrumentation, Wroclaw University of Technology, Wroclaw, Poland
  • Peter Smielewski - Academic Neurosurgery Unit, Addenbrooke's Hospital, Cambridge University, Cambridge, United Kingdom
  • Marek Czosnyka - Academic Neurosurgery Unit, Addenbrooke's Hospital, Cambridge University, Cambridge, United Kingdom

Deutsche Gesellschaft für Neurochirurgie. Society of British Neurological Surgeons. 68. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), 7. Joint Meeting mit der Society of British Neurological Surgeons (SBNS). Magdeburg, 14.-17.05.2017. Düsseldorf: German Medical Science GMS Publishing House; 2017. DocMO.08.07

doi: 10.3205/17dgnc048, urn:nbn:de:0183-17dgnc0485

Published: June 9, 2017

© 2017 Lang et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 License. See license information at http://creativecommons.org/licenses/by/4.0/.

Outline

Text

Objective: The ICP pulse waveform changes with rising ICP. This is thought to indicate changing both intracranial and cerebrovascular compliances, which may be clinically useful above the ICP value itself. An increasing High Frequency Centroid (HFC), the power-weighted average frequency within the 4 to 15-Hz band of the ICP power density spectrum has been reported to correlate with rising ICP. We examine this concept and introduce another centroid, the high harmonic centroid HHC, potentially less dependent of heart rate (HR). HHC is the center of mass of its harmonics from 2nd to 10th expressed as consecutive integers, where mass corresponds to amplitudes of these harmonics.

Methods: From the 325-patient Cambridge TBI 2002 to 2010 database containing patients whose high resoloution ICP and ABP signals were recorded with a bedside computer system, we extracted 26 patients with ICP plateau waves and calculated HFC and HHC utility in 2 steps: (1) We investigated the correlations between HFC/HHC and ICP, arterial blood pressure (ABP), cerebral perfusion pressure (CPP), HR and PRx, a cerebral autoregulation index. (2) We calculated HFC/HHC and their correlations with ICP, CPP, ABP, and HR during isolated ICP plateauwaves to compare baseline values of centroids with ICP plateau wave peak values.

Results: (1) For the whole monitoring period ICP (22±7mmHg) correlates significantly with its centroids (R=0.42, p=0.035 for HFC (7.72±0.45Hz); R=0.45, p=0.022 for HHC (3.64±0.46). ABP (96±10mmHg) also correlates significantly with HFC/HHC (R=0.627, p=0.001, HFC; R=0.5, p=0.009, HHC). CPP (75±7mmHg) correlates significantly with HFC R=0.46, p=0.019) but not with HHC. PRx (0.03±0.19) doesn’t correlate significantly with any centroid. (2) During the ICP plateauwaves we found significant HFC and HHC decreases at baseline vs. peak (ICP: 22±7mmHg vs. 55±13mmHg; HFC: 7.7±0.46Hz vs. 7.55±0.6Hz; HHC: 3.72±0.54 vs. 3.17±0.37).

Conclusion: This study confirms the utility of computerized ICP pulse waveform analysis. In contrast to previously reported data high frequency centroids decreases at high ICPs. Further studies are needed to identify individual ICP-HFC/HHC breakpoints and their potential clinical utility.