Wavelet analysis of the effects of prolonged loading on the variations of hemoglobin oxygenation: Investigation using an in vivo rat model

Zengyong Li, Wing Cheung Eric Tam, Arthur F.T. Mak, Roy Y.C. Lau

Research output: Journal article publicationConference articleAcademic researchpeer-review


The consequences of rhythmical flow motion for nutrition and the oxygen supply to tissue are largely unknown. In the study presented here, the periodic variations of hemoglobin oxygenation in both compressed and uncompressed skin were evaluated with a reflection spectrometer using an in vivo Sprague-Dawley rat model. Skin compression was induced over the trochanter area by locally applied external pressure of 13.3kPa (100 mmHg) via a specifically designed pneumatic indentor. Loading duration is 6 hours per day for 4 consecutive days. A total of 19 rats were used in this study. For quantification of the change in periodic variations of hemoglobin oxygenation, spectral analysis based on wavelets transformation was used. Periodic variations of the hemoglobin oxygenation with two characteristic frequencies in the range of 0.01- 0.05 Hz and 0.15-0.4 Hz were found in both compressed and uncompressed skin, which coincide with the frequency range of the endothelial related metabolic and myogenic activities found in the flow motion. The results showed that tissue compression following the above schedule induced a significant decrease in the spectral amplitudes of frequency interval 0.01- 0.05 Hz during the pre-occlusion period on day 3 and day 4 as compared to that on day 1 (p<0.05). However, prolonged compression induced a significant increase in spectral amplitude of frequency interval 0.15-0.4 Hz during the pre-occlusion period in the compressed tissue on day 3 (p=0.041) and day 4 (p=0.01) compared to that in the uncompressed tissue on day 1. The results indicated that the variations of the hemoglobin oxygenation were closely related to the endothelial related metabolic and myogenic activities. The spectral amplitude of variations of hemoglobin oxygenation was shown to be enhanced in the frequency range of 0.15-0.4 Hz. This might substantially affect the available oxygen supply to the compressed tissues.
Original languageEnglish
Pages (from-to)2832-2834
Number of pages3
JournalIFMBE Proceedings
Issue number1
Publication statusPublished - 1 Jan 2007
Event10th World Congress on Medical Physics and Biomedical Engineering, WC 2006 - Seoul, Korea, Republic of
Duration: 27 Aug 20061 Sep 2006


  • Flow motion
  • Hemoglobin oxygenation
  • Prolonged compression
  • Spectral analysis
  • Wavelet transform

ASJC Scopus subject areas

  • Bioengineering
  • Biomedical Engineering

Cite this