[Observations of capillary fluid flow rate by vibration on the small vessel model]

The vibration hazards in peripheral blood vessels as an occupational origin is caused by using pneumatic vibrating tools. In order to know that the major part of causes is whether due to the direct effects of the physical vibration or due to the effects depended on the excitations of peripheral nervous system, an model experiment was employed to estimate the direct effect of the physical vibration. In our experiments, water as fluid was used instead of blood. The silicon capillary tube as same the physical qualities and conditions as blood vessels was vibrated by oscillator. The silicon capillary tube was exposed by following three type of vibration mode to flow axis; i) sine wave of transverse vibration, ii) rectangular wave of transverse vibration, and iii) sine wave of longitudinal vibration. The range of vibration frequency covered 1-2000 Hz. The averaged acceleration by oscillating vibration and the vibration strength level were estimated about 1-200 G and 150 dB, respectively. The observed decreases of water flow rate due to vibration extremely depend on frequency. The decrease ratio of water flow rate by vibration was at maximum 12% down compare with the cases of non vibration. In these observed results by this model experiment, it should be concluded that the direct effect of the physical vibration to the blood flow was not too strong to cause the actual vibration hazards.