Effects of prolonged surface pressure on the skin blood flowmotions in anaesthetized rats—an assessment by spectral analysis of laser Doppler flowmetry signals

Abstract

The objective of this study is to assess the effect of prolonged surface compression on the skin blood flowmotion in rats using spectral analysis based on wavelets transform of the periodic oscillations of the cutaneous laser Doppler flowmetry (LDF) signal. An external pressure of 13.3 kPa (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. Five frequency intervals were identified (0.01-0.04 Hz, 0.04-0.15 Hz, 0.15-0.4 Hz, 0.4-2 Hz and 2-5 Hz) corresponding to endothelial related metabolic, neurogenic, myogenic, respiratory and cardiac origins. The absolute amplitude of oscillations of each particular frequency interval and the normalized amplitude were calculated for quantitative assessments. The results showed that (1) tissue compression following the above schedule induced significant decrease in the normalized amplitude in the frequency interval of 0.01-0.04 Hz both in the trochanter area (p < 0.001) and tibialis area (p = 0.023), (2) prolonged compression induced significant increase in the absolute amplitude (p = 0.004 for the trochanter area and p = 0.017 for the tibialis area) but significant decrease in the normalized amplitude (p = 0.023 for the trochanter area and p = 0.026 for the tibialis area) in the frequency interval of 0.15-0.4 Hz, and (3) at the tibialis area, the flowmotion amplitude (frequency interval 0.15-0.4 Hz) measured prior to the daily tissue compression schedule was found to be significantly higher on day 4 than the measurements obtained on day 1. However, this finding was not observed at the trochanter area. Our results suggested that prolonged compression might induce endothelial damage and affect the endothelial related metabolic activities.

Deep tissue injury rat model for pressure ulcer research on spinal cord injury

“…Li's report further confirmed our concern that animals in SCI condition respond to pressure injury in a different pattern than that of the neurologically intact animals, therefore, emphasized the needs to conduct PU related animal research on an animal model which possesses the concerned pathophysiological condition, which in this case, spinal cord injury. However, it should be pointed out that this single SCI rat PU model may have some controversy in that their creation of SCI was a unilateral hemisection of spinal cord at C730 while their observation of tissue injury and blood flow was performed bilaterally at trochanter 14. Another concern for this SCI rat model is that there was no clear description whether the SCI condition was acute or chronic.…”

Local cooling reduces skin ischemia under surface pressure in rats: an assessment by wavelet analysis of laser Doppler blood flow oscillations

“…Spectral analysis has recently been introduced to investigate the regulatory mechanisms of skin blood flow in response to pressure or thermal stress (Li et al 2006, Jan et al 2008). bBlood flow oscillations measured with spectral analysis in human beings has revealed five characteristic frequencies (Stefanovska et al 1999).…”

Relationship between Myogenic Reaction and Autoregulation of Cerebral Circulation

“…According to published reports, the following frequency ranges were identifi ed for rats: 0.01-0.04 Hz for endothelial NO, 0.04-0.15 Hz for neuronal sympathetic infl uences, and 0.15-0.4 Hz for myogenic tone [7]. A LAKK-01 device (Lazma) was used in the experiments.…”