Effect of External Pressure on Skin Blood Flow at Lower Limb in Different Postures

The influence of garment pressure on human physiological activities has attracted researchers from many areas. In this study, to investigate the effect of external pressure on skin blood flow (SBF) at lower limb due to different postures, external pressure was exerted on lower limb with supine and sitting postures respectively by using sphygmomanometer. Five undergraduate male students volunteered to participate in the study. An alternating pressure loading protocol between non-pressure and pressure of 20mmHg or 40mmHg was employed. The SBF undergoing pressure was observed with Laser Doppler Flowmeter. It was found that the SBF increased under low pressure and began to decrease as the pressure exceeded a certain level (around 35mmHg). It was speculated that the SBF change due to external pressure was the result of balance between the neural effect and mechanical effect. The blood pressure with supine posture was lower than that with sitting posture, thus the blood pressure in metarterioles was lower with supine posture and thereby the SBF began to decrease under lower pressure with supine posture than that with the sitting posture. In view of microcirculation, high pressure can be an obstacle, particularly with supine posture. The findings will be helpful for the design and application of tight-fit garments.