Long-term periodic monitoring of cardiovascular function in unobtrusive way has been a challenge in sensor research lately. This work presents the investigation of the method for pulse arrival time (PAT) estimation using body composition scales. It employs the electrocardiogram and the impedance plethysmogram (IPG) which are recorded from palm and plantar electrodes already integrated into body composition scales. Four subjects were involved in the experiment. The IPG was acquired from a single-foot and foot-to-foot and compared to the reference method — photoplethysmography. The range of correlation coefficient obtained in different methods varied from 0.7 to 0.94 showing that small PAT variations can be tracked using the IPG signals. Such results suggest that body composition scales could be supplemented with additional parameter for the assessment of arterial stiffness. This function will make them truly multi-parametric device for periodic health monitoring at home

1. Estimation of Pulse Arrival Time Using
Impedance Plethysmogram from Body
Composition Scales
Birutė Paliakaitė1, Saulius Daukantas2, Andrius Sakalauskas2,
Vaidotas Marozas1,2
1Department of Electronics Engineering, Kaunas University of Technology
2Biomedical Engineering Institute, Kaunas University of Technology
April 13-15, 2015

2. Motivation
Arterial stiffness leads to the development of
cardiovascular morbidity and mortality1.
Central (aortic) stiffness:
– elderly subjects,
– end-stage renal disease,
– hypertension,
– impaired glucose tolerance.
Peripheral (lower-limbs) stiffness:
– peripheral artery disease,
– diabetic peripheral neuropathy.
1/141S. Laurent et al. Expert consensus document on arterial stiffness: methodological issues and
clinical applications. Eur. Heart J., vol. 27, no. 21, 2006.

3. Motivation
Arterial stiffness leads to the development of
cardiovascular morbidity and mortality.
Central (aortic) stiffness1:
– elderly subjects,
– end-stage renal disease,
– hypertension,
– impaired glucose tolerance.
Peripheral (lower-limbs) stiffness:
– peripheral artery disease,
– diabetic peripheral neuropathy.
1/141S. Laurent et al. Expert consensus document on arterial stiffness: methodological issues and
clinical applications. Eur. Heart J., vol. 27, no. 21, 2006.

4. Motivation
Arterial stiffness leads to the development of
cardiovascular morbidity and mortality.
Central (aortic) stiffness:
– elderly subjects,
– end-stage renal disease,
– hypertension,
– impaired glucose tolerance.
Peripheral (lower-limbs) stiffness:
– peripheral artery disease2,
– diabetic peripheral neuropathy3.
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2H. Yokoyama et al. Pulse wave velocity in lower-limb arteries among diabetic patients with
peripheral arterial disease. J. Atheroscler. Thromb., vol. 10, no. 4, 2003.
3M. Edmonds et al. Blood flow in the diabetic neuropathic foot. Diabetologia, vol. 22, no. 1, 1982.

5. Background
Arterial stiffness can be characterized by the
propagation of the pulse pressure wave (PPW) along
the arterial tree.
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6. Background
Arterial stiffness can be characterized by the
propagation of the pulse pressure wave (PPW) along
the arterial tree.
Pulse arrival time (PAT) – the time interval between the
R-wave of the QRS complex and the particular point in
the PPW.
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7. Background
Arterial stiffness can be characterized by the
propagation of the pulse pressure wave (PPW) along
the arterial tree.
Pulse arrival time (PAT) – the time interval between the
R-wave of the QRS complex and the particular point in
the PPW.
2/14

8. Background
Arterial stiffness can be characterized by the
propagation of the pulse pressure wave (PPW) along
the arterial tree.
Pulse arrival time (PAT) – the time interval between the
R-wave of the QRS complex and the particular point in
the PPW.
2/14

9. Background
Arterial stiffness can be characterized by the
propagation of the pulse pressure wave (PPW) along
the arterial tree.
Pulse arrival time (PAT) – the time interval between the
R-wave of the QRS complex and the particular point in
the PPW.
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PAT
Arterial stiffness

10. Problem
Long-term periodic monitoring needed
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11. Problem
Long-term periodic monitoring needed
Available devices for PPW recording
3/14

12. Problem
Long-term periodic monitoring needed
Available devices for PPW recording
Illustration retrieved from http://www.atcormedical.com/
3/14

13. Problem
Long-term periodic monitoring needed
Available devices for PPW recording
Illustrations retrieved from http://www.atcormedical.com/
3/14

14. Problem
Long-term periodic monitoring needed
Available devices for PPW recording
Illustrations retrieved from http://www.atcormedical.com/
3/14

15. Problem
Long-term periodic monitoring needed
Available devices for PPW recording
Illustrations retrieved from http://www.atcormedical.com/ and http://www.atcormedical.com/
3/14

16. Problem
Long-term periodic monitoring needed
Available devices for PPW recording:
Illustrations retrieved from http://www.atcormedical.com/ and http://www.atcormedical.com/
Operator dependent
Results rely on the placement
3/14

17. New Approach (1)
Impedance plethysmography (IPG) to determine
changing tissue volumes (e.g. blood)
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∆𝑹 = 𝝆
𝒍 𝟐
∆𝒗

18. New Approach (1)
Impedance plethysmography (IPG) to determine
changing tissue volumes (e.g. blood).
ECG and IPG electrodes integrated into unobtrusive
devices (e.g. bathroom scales)
4/14
𝑹 = 𝝆
𝒍
𝑨
Illustration retrieved from OMRON HBF-510 Instruction Manual

19. New Approach (2)
The lower-body IPG signals are the sum of the local
impedances of all segments between the voltage
electrodes,
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20. New Approach (2)
The lower-body IPG signals are the sum of the local
impedances of all segments between the voltage
electrodes,
5/14Illustration retrieved from O. G. Martinsen, S. Grimnes, Bioimpedance and Bioelectricity Basics,
2nd ed., London: Academic Press, 2008.
but the influence of the lower parts is
the greatest.

21. New Approach (2)
The lower-body IPG signals are the sum of the local
impedances of all segments between the voltage
electrodes,
5/14Illustration retrieved from O. G. Martinsen, S. Grimnes, Bioimpedance and Bioelectricity Basics,
2nd ed., London: Academic Press, 2008.
but the influence of the lower parts is
the greatest.
The goal of this study is to
demonstrate that PAT from the heart
to the foot can be estimated using
ECG and IPG recorded on
the bathroom scales.

22. Measurement Setup
Body composition scales (Omron)
ECG: wireless ECG transmitter (Biopac)
IPG: electrical bioimpedance unit (Biopac)
IPG: photoplethysmogram amplifier unit
(Biopac)
Illustration retrieved from OMRON HBF-510 Instruction Manual
6/14

23. Measurement Setup
Body composition scales (Omron)
ECG: wireless ECG transmitter (Biopac)
IPG: electrical bioimpedance unit (Biopac)
IPG: photoplethysmogram amplifier unit
(Biopac)
Illustration retrieved from OMRON HBF-510 Instruction Manual
6/14

24. Measurement Setup
Body composition scales (Omron)
ECG: wireless ECG transmitter (Biopac)
IPG: electrical bioimpedance unit (Biopac)
IPG: photoplethysmogram amplifier unit
(Biopac)
Illustration retrieved from OMRON HBF-510 Instruction Manual
6/14

25. Measurement Setup
Body composition scales (Omron)
ECG: wireless ECG transmitter (Biopac)
IPG: electrical bioimpedance unit (Biopac)
PPG: photoplethysmogram amplifier unit
(Biopac)
Illustration retrieved from OMRON HBF-510 Instruction Manual
6/14

26. Methods
Four healthy subjects (one woman)
Paced respiration (0.1 Hz) to cause hemodynamics
changes
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27. Methods
Four healthy subjects (one woman)
Paced respiration (0.1 Hz) to cause hemodynamics
changes
7/14

28. 50 kHz
400 µArms
V
Methods
Four healthy subjects (one woman)
Paced respiration (0.1 Hz) to cause hemodynamics
changes
foot-to-foot single-foot
Illustration retrieved from OMRON HBF-510 Instruction Manual
Measurement cases
7/14

29. 50 kHz
400 µArms
V
Methods
Four healthy subjects (one woman)
Paced respiration (0.1 Hz) to cause hemodynamics
changes
foot-to-foot single-foot
Illustration retrieved from OMRON HBF-510 Instruction Manual
Measurement cases
7/14

30. 50 kHz
400 µArms
V
Methods
Four healthy subjects (one woman)
Paced respiration (0.1 Hz) to cause hemodynamics
changes
foot-to-foot single-foot
Illustration retrieved from OMRON HBF-510 Instruction Manual
Measurement cases
7/14

31. Signal Processing
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32. Signal Processing
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33. Signal Processing
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34. Signal Processing
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35. Signal Processing
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36. Signal Processing
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37. Results: example of the signals
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Foot-to-foot caseSingle-foot case

38. Results: example of the estimated PAT
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Single-foot case
Foot-to-foot case

39. Results: example of estimated PAT
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Single-foot case
Foot-to-foot case

40. Results: example of estimated PAT
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Single-foot case
Foot-to-foot case

41. Results: example of estimated PAT
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Single-foot case
Foot-to-foot case

42. Results: foot-to-foot vs. single-foot
Data represent mean±SD 11/14

43. Results: foot-to-foot vs. single-foot
Data represent mean±SD 11/14

44. Results: boxplot of the absolute values
of PAT
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45. Results: boxplot of the absolute values
of PAT
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46. Results: boxplot of the absolute values
of PAT
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47. Results: boxplot of the absolute values
of PAT
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48. System Implementation
Custom-made bioimpedance unit integrated into body
composition scales
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49. Conclusions and Future Directions
Conclusions
– PAT can be estimated by using IPG and ECG sensors, which are integrated
into body composition scales;
– PAT evaluated by the method introduced in this study correlates with
PPG-based PAT;
– single-foot and foot-to-foot PATIPG slightly differs.
Future directions
– testing of the custom-made system;
– development of the algorithm for the calculation of PAT;
– a wider group of subjects with different health status.
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50. Acknowledgment
This work was partly supported by the projects
“Promotion of Student Scientific Activities” (VP1-3.1-
ŠMM-01-V-02-003) from the Research Council of
Lithuania and CARRE (No.611140) funded by the
European Community 7th Framework Programme.

51. Thank you
for your attention