Trends of reactive hyperaemia responses to repetitive loading on skin tissue of rats – Implications for pressure ulcer prevention

Abstract

Tissue recovery is important in preventing tissue deterioration, which is induced by pressure and may lead to pressure ulcers (PU). Reactive hyperaemia (RH) is an indicator used to identify people at risk of PU. In this study, the effect of different recovery times on RH trend is investigated during repetitive loading. Twenty-one male Sprague-Dawley rats (seven per group), with body weight of 385-485 g, were categorised into three groups and subjected to different recovery times with three repetitive loading cycles. The first, second, and third groups were subjected to short (3 min), moderate (10 min), and prolonged (40 min) recovery, respectively, while fixed loading time and pressure (10 min and 50 mmHg, respectively). Peak hyperaemia was measured in the three cycles to determine trends associated with different recovery times. Three RH trends (increasing, decreasing, and inconsistent) were observed. As the recovery time is increased (3 min vs. 10 min vs. 40 min), the number of samples with increasing RH trend decreases (57% vs. 29% vs. 14%) and the number of samples with inconsistent RH trend increases (29% vs. 57% vs. 72%). All groups consists of one sample with decreasing RH trend (14%). Results confirm that different recovery times affect the RH trend during repetitive loading. The RH trend may be used to determine the sufficient recovery time of an individual to avoid PU development.

Determining weight‐bearing tissue condition using peak reactive hyperemia response trend and ultrasonographic features: Implications for pressure ulcer prevention

“…Previous studies have used peak RH over a single cycle to determine the severity of tissue ischemia induced by pressure application . Increased peak RH generally correlates with the increased level of ischaemic damage; decreased peak RH correlates with the increased level of endothelial dysfunction; whereas inconsistent peak RH over time correlates with the weight‐bearing tissue recovery . In the present study, the use of successive peak RH over three repetitive loadings forming RH trends are compared with the tissue condition under histopathological examination to validate the results made in previous studies where the increasing and decreasing RH trends are associated with tissue damage; while the inconsistent RH trend is associated with tissue recovery.…”

“…On the other hand, the inconsistent RH trend is associated with normal tissues. The inconsistent RH trend probably due to the development of collateral vessels at weight‐bearing tissues on a condition wherein ischemic event is reversed . This study shows most of the subjects with inconsistent RH trend were accompanied with normal tissue and this appears the inconsistent RH trend to be a suitable skin blood flow feature to indicate full damage reversal of weight‐bearing tissues that might not leading to PU development.…”

“…The short to prolonged recovery time (3 minutes to 40 minutes) provides different degree of recovery to compensate the damages induced by pressure. The recovery times of 3, 10, and 40 minutes are able to obtain samples with tissues condition of accumulated damage to recovery stage as the results shown in Yapp et al study . All animals were randomized into repetitive loading application by picking numbers out of hat with maximum seven rats for each recovery time application, according to whichever the desired age and weight of an animal was reached.…”

“…This analysis was performed using MATLAB (version 8.5.0; The Mathworks, Inc.) software. Peak RH during three repetitive loading‐recovery cycles were extracted from the filtered skin perfusion signal and a trend is established by joining the three peaks with straight lines accordingly, as shown in Figure . The RH trend results for each samples are listed in Table .…”

Skin Blood Flow Response Signal Using Time and Frequency Domain Features for Pressure Ulcer Evaluation

“…In order to resolve the optimal duration of the repositioning, the relationship between the repositioning duration and tissue condition is under active investigation. In evaluating the tissue conditions , the skin blood flow response (SBFR) signal and their trends over several repetitive loading -unloading cycles have been studied [22].…”