Effect of prolonged pressure on flowmotion: An Investigation Using an in vivo Rat Model

The objectives of this study is to assess the effect of prolonged loading on the skin blood flowmotion in rats as measured by Laser Doppler flowmetry (LDF) using wavelets transform and power spectral in the rat skin microcirculation. External pressure of 13.3kPa (100 mmHg) was applied to the trochanter area and the distal lateral tibia of Sprague-Dawley rats via two specifically designed pneumatic indentors. The loading duration was 6 hours/day for 4 consecutive days. The results showed that 1) spontaneous rhythmic activities were present in skin blood flow of anesthetized rats, 2) significant decrease of flowmotion power (p=0.023 for trochanter and p=0.043 for tibia) was found in the frequency range of 0.01-0.04Hz after prolonged loading. Our results suggested that reduced vasomotion in the frequency of 0.01-0.04 Hz might be involved in the mechanisms leading to pressure ulcer formation.