Study of bubbles formation in organic tissue subjected to pressure variation environments and bubble embolism

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Bubbles often generate in organic tissue subjected to pressure variation of environments, and consequently the bubbles are responsible for bubble embolism. In this work, the experimental studies are conducted from viewpoint of fluid dynamics in order to clarify decompression disease such as submarine sickness and complication after substitution of an artificial heart valve.(1)During the flow in the pipe with small diameter of 1.15mm, the bubbles of diameter 0.06mm〜0.84mm are generated in oversaturated liquid-gas solutions (oxygen, carbon dioxide, helium). The incorporation phenomena of bubbles and the formation of chain bubbles are also observed. The number of bubbles increase with increasing of gas additional pressure and flow velocity in pipe. In the liquids solved carbon dioxide, the size and the number of occurring bubbles are larger than the case in oxygen and helium. The bubbly flow in the small pipe may be cause of obstruction an of arteriola and venula.(2)In soft organic tissue such as musclar model and fat moder under the conditions of high gas pressure, the bubbles also occur. Carbon dioxide bubbles are easy to make in fat model, and the number of bubble density of helium is large as compare with the cases of oxygen, carbon dioxide.(3)Cavitation phenomena are detected around an artificial valve in pulsatile flow with high velocity. In the conditions of flow rate Q=5L/min and mean flow velocity v=0.57m/s, cavitation bubbles are observed in downstream of aortic valve. The bubbles of the size of 0.2mm〜0.5 mm are detected around aortic valve, and the velocities of movement of the bubbles are 0.46m/s〜1.2m/s. On the upstream side of aortic valve, cavitation phenomena are produced explosively at closing of the valve. The small bubbles produced around artificial valve are responsible for embolism in cardiovascular system and HITS.