Testing Validity of Evaluating Skin Blood Perfusion by Our Developed Device in the Elderly

Friday, 28 July 2017

Aki Ibe, PhD1
Yoko Aso, PhD2
Tomoyuki Haga, BE3
Masako Miyajima, PhD2
Aino Hayashi, MSN1
Megumi Katayama, PhD2
Kaori Fujimoto, MS4
Mihoko Ishizawa, PhD5
Kazuhiro Takeda, LLB6
(1)Faculty of Nursing Science, Tsuruga Nursing University, Tsuruga, Japan
(2)Graduate School of Nursing/School of Nursing, Mukogawa Women's University, Nishinomiya, Japan
(3)Emertech Co., Ltd., Kobe, Japan
(4)School of Nursing, Mukogawa Women's University, Nishinomiya, Japan
(5)Faculty of Nursing/ Graduate School of Nursing, Nara Medical University, Kashihara, Japan
(6)Rainbow & i Co.Ltd., Yokosuka, Japan


Nurses play an important role in the prevention of pressure ulcers. However, because the determination of stage 1 (the early status of pressure ulcers) is based on the appearances of such ulcers, nurses have difficulty determining their presence. In our previous study, one out of three Japanese nurses admitted having difficulty judging stage 1 by themselves. In addition, no simple device exists with which nurses can directly evaluate the status of skin blood perfusion. Given the leading role that blood flow plays in the transfer of body heat, we focused on the heat transfer efficiency of skin tissue, and developed a device for evaluating the blood perfusion. Heating in the local area of the skin surface, the skin-surface temperature response depends on the amount of blood perfusion. We estimated the skin blood perfusion by solving the bio-heat transfer equation with skin-surface temperature responses.

In this study, we experimentally tested the validity of evaluations made with our new device and compared its estimated skin blood perfusion with the measured values of the Laser Tissue Blood Flowmeter (OMEGAFLO, OMEGAWAVE, INC.) of the feet of participants covered by a blanket, which was a Japanese futon.


 Twenty healthy elderly people participated (10 men and 10 women) wore 100% cotton pajamas and lay in bed in a climate chamber. The ambient temperature and relative humidity were controlled at 25°C and 55% RH. The subjects lay in bed for 30 minutes with their body and extremities covered by a blanket and for another 15 minutes without a blanket covering from their knees down. We measured the skin-surface temperature and the superficial blood flow by the flowmeter on the sole of feet at the following three times: just before the body and extremities were covered with a blanket (before), 30 minutes after being covered with a blanket (after being covered), and 15 minutes after it was removed from below the knee (without blanket). We estimated the blood perfusion with skin-surface temperature responses and compared it with the flowmeter value.


 The mean (S.D.) age of the subjects was 71.5 (3.6) years. The mean (S.D.) skin-surface temperature was 31.8 (1.8) °C before being covered, 33.7 (2.0) °C after being covered, and 31.7 (1.7) °C without a blanket. The mean (S.D.) estimated blood perfusion by the proposed device was 0.8 (0.3) before, 1.6 (1.6) after being covered, and 0.8 (0.2) without a blanket. The mean (S.D.) flowmeter value was 8.4 (4.4) before, 10.4 (5.3) after being covered, and 7.7 (4.6) without a blanket. Like the skin-surface temperature and the flowmeter value, the estimated blood perfusion significantly increased after being covered with a blanket and significantly decreased after it was removed. Positive correlations were observed between the estimated blood perfusion with the flowmeter value (r=0.49, p<0.05). But no relationship was observed between the ratios of the change (before and after being covered with a blanket) of the estimated blood perfusion and the flowmeter.


We confirmed the ability of our new device to evaluate skin blood perfusion. With it, we will be able to objectively and easily predict pressure ulcer developments. However, we found no relationship between the ratio of the change of the estimated blood perfusion and the flowmeter value. The validity of evaluating skin blood perfusion must also be investigated in further study.