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Wavelet Components of Photoplethysmography During Reactive Hyperemia: Absolute vs. Relative Metrics
Henrique Silva1,2,3, Nicole Lavrador2
1Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisbon, Portugal.
Biology
|December 30, 2025
Summary
This study compared absolute power and relative contribution of photoplethysmography (PPG) signals during reactive hyperemia. Findings show these metrics capture different microvascular regulation aspects, highlighting the need for consistent analysis methods.
Area of Science:
- Physiology
- Biomedical Engineering
- Vascular Biology
Background:
- Photoplethysmography (PPG) non-invasively measures blood volume pulsations.
- Wavelet transform (WT) decomposes PPG into frequency bands reflecting physiological activities.
- Spectral analysis of PPG can use absolute power or relative contribution.
Purpose of the Study:
- To compare absolute power and relative contribution metrics of PPG signals.
- To assess microvascular regulation during post-occlusive reactive hyperemia (PORH).
- To evaluate the physiological interpretation of wavelet-derived PPG analyses.
Main Methods:
- PPG signals recorded bilaterally in 12 healthy adults during baseline, occlusion, and recovery.
- Wavelet transform used to decompose PPG into physiological frequency bands.
- Spectral power and percent contribution calculated for each band and phase.
Main Results:
- Occlusion suppressed higher-frequency oscillations but enhanced endothelial activity.
- Hyperemia increased respiratory and endothelial oscillations above baseline.
- Absolute power correlated with perfusion magnitude; relative contribution reflected spectral redistribution.
Conclusions:
- Absolute power and relative contribution metrics are complementary but not equivalent.
- Different metrics capture distinct aspects of microvascular regulation.
- Methodological consistency is crucial for interpreting wavelet-derived PPG data.
Keywords:
endothelial functionphotoplethysmographyreactive hyperemiaskin microcirculationspectral analysisvasomotionwavelet transformMore Related Videos
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