gms | German Medical Science

28. Wissenschaftlicher Kongress der Deutschen Hochdruckliga

24. bis 27.11.2004, Hannover

Beat-to-beat measurement of continuous NIBP by pulse wave velocity and transit time for diagnosing and monitoring hypertension

Nicht invasive, fortlaufende Puls für Puls Messung des art. Blutdruckmittels Laser-Doppler-Flowmetrie zum Hypertoniemonitoring

Meeting Abstract (Hypertonie 2004)

  • M.H. Brem - Friedrich-Alexander Universität Erlangen-Nürnberg
  • P. Boll - Friedrich-Alexander Universität Erlangen-Nürnberg
  • W. Stork - Friedrich-Alexander Universität Erlangen-Nürnberg
  • K.D. Müller-Glaser - Friedrich-Alexander Universität Erlangen-Nürnberg
  • J. Schüttler - Friedrich-Alexander Universität Erlangen-Nürnberg
  • N. Lutter - Friedrich-Alexander Universität Erlangen-Nürnberg

Hypertonie 2004. 28. Wissenschaftlicher Kongress der Deutschen Hochdruckliga. Hannover, 24.-27.11.2004. Düsseldorf, Köln: German Medical Science; 2005. Doc04hochP83

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Veröffentlicht: 10. August 2005

© 2005 Brem et al.
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Background and Goal of Study: Arterial blood pressure (BP) essentially relies on the pulse wave velocity (PWV), the pulse transit time (PTT), the arterial diameter and the reflection coefficient and thus can be estimated beat-to-beat by determining the PWV and the PTT.

Materials and Methods: After IRB approval and informed consent, 56 patients (ASA physical status II-IV, average age 67y) scheduled for cardiovascular surgery were included. A prototype sampled, processed and visualized the laser Doppler flow (LDF), the ECG (Einthoven I), and the referential BP of the contralateral A. radialis. The LDF detector was placed at the index finger. PTT and PWV were calculated beat-to-beat by the utilizing the time interval between the ECG's R-wave and the foot points (FP) of the LDF. The FP is represented by the intersection of the tangent lines as referred to the natural FP at zero inclination and to the point of maximum inclination. The information of these typical segments of the waveform provides for a robust and thus more appropriate input towards BP determination. To improve the detection of the R wave the first derivative of the QRS complex was used after linear recursive interpolation. Initially, calibration of the prototype was performed through the patient monitor. Prior to offline determination of the BP artifactual data have been removed. Overall, 67245 arterial pulse waveforms were considered for analysis.

Results and Discussions: Noninvasive quasi-continuous BP and referential invasive BP yield correlation coefficients of RLDF=0.89 (Psys), RLDF=0.87 (Pm), and RLDF=0.80 (Pdia). Student's testing does not prove a significant difference between corresponding Rs (P<0.05). Bland-Altman testing (LDF vs. invasive reference) returns SDs of ±5.73mmHg (Psys), ±3.21mmHg (Pm) and ±2.29mmHg (Pdia).

Conclusion: The noninvasive beat-to-beat calculation of BP by measuring the PWV and the PTT seems to be an appropriate method for diagnosis and monitoring of hypertension.