Pressure ulcers are a significant healthcare problem affecting the quality of life in wheelchair bounded or bed-ridden people and are a major cost to the healthcare system. Various assessment tools such as the Braden scale have been developed to quantify the risk level of pressure ulcers. These tools have provided an initial guideline on preventing pressure ulcers while additional assessments are needed to improve the outcomes of pressure ulcer prevention. Skin blood flow function that determines the ability of the skin in response to ischemic stress has been proposed to be a good indicator for identifying people at risk of pressure ulcers. Wavelet spectral and nonlinear complexity analyses have been performed to investigate the influences of the metabolic, neurogenic and myogenic activities on microvascular regulation in people with various pathological conditions. These findings have contributed to the understanding of the role of ischemia and viability on the development of pressure ulcers. The purpose of the present review is to provide an introduction of the basic concepts and approaches for the analysis of skin blood flow oscillations, and present an overview of the research results obtained so far. We hope this information may contribute to the development of better clinical guidelines for the prevention of pressure ulcers.

To test for an active vasodilator system in human hand and finger skin, seven subjects had a small area of dorsal hand, palm, or dorsal finger pretreated with bretylium (BT) to block adrenergic vasoconstriction. Skin blood flow was monitored at a BT-treated site, a comparable untreated site, and the forearm by laser-Doppler flowmetry. Cutaneous vascular conductance (CVC) was evaluated from the ratio of blood flow to arterial pressure. Body cooling, to evaluate vasoconstrictor system blockade, caused CVC at untreated sites of forearm, palm, dorsal hand, and dorsal finger to fall by 45 +/- 4, 85 +/- 5, 51 +/- 9, and 63 +/- 7%, respectively (all P < 0.05). At BT-treated sites of palm, dorsal hand, and dorsal finger, reductions in CVC were only 13 +/- 3, 2 +/- 18, and 13 +/- 4%, respectively (dorsal hand not significant, others P < 0.05). With body heating, increases in CVC at untreated sites of forearm, palm, dorsal hand, and dorsal finger were 881 +/- 165, 779 +/- 368, 423 +/- 115, and 1,430 +/- 716%, respectively (all P < 0.05). At BT-treated sites of palm, dorsal hand, and dorsal finger, increases were 35 +/- 15, 342 +/- 107, and 343 +/- 34%, respectively (palm not significant, others P < 0.05). Increased CVC at the palm began after 1.2 +/- 0.2 min of heating, significantly earlier than forearm (11.8 +/- 2.5 min), dorsal hand (16.4 +/- 3.4 min), or dorsal finger (15.6 +/- 3.6 min), which did not differ significantly from one another.(ABSTRACT TRUNCATED AT 250 WORDS)

Cupping therapy has been widely used in treating musculoskeletal impairments. However, there is no specific guideline on selecting the intensity of cupping therapy, including the pressure and duration. The objective of this study was to investigate the effect of different pressures and durations of cupping therapy on skin blood flow responses. A 2 × 2 factorial design, including two negative pressures at −225 and −300 mmHg and two durations at 5 and 10 min, was tested in 12 healthy participants. The four protocols of cupping therapy were tested in four different days. Skin blood flow was measured using laser Doppler flowmetry on the left triceps (the SJ12 acupoint). Skin blood flow after cupping therapy was expressed as a ratio of skin blood flow before cupping therapy. The results showed that −300 mmHg caused a significant increase in peak skin blood flow (16.7 ± 2.6 times) compared to −225 mmHg (11.1 ± 2.2 times, p &lt; 0.05) under 5-min duration. The largest difference in skin blood flow is between −300 mmHg for 5 min (16.7 ± 2.6 times) and −225 mmHg for 10 min (8.1 ± 2.3 times, p &lt; 0.01). Our findings demonstrated that a higher value (300 mmHg) of negative pressure is more effective on increasing skin blood flow compared to a lower value (225 mmHg). Also, a shorter duration (5 min) causes a larger peak and total skin blood flow compared to a longer duration (10 min). This study provides the first evidence showing the effect of pressures and durations of cupping therapy on skin blood flow responses.

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