Quantitative reliability of graft flow measured by a cuff-type electromagnetic flowmeter probe

概要

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In our ventricular assist device system, the bypass flow is measured by an electromagnetic flowmeter, the probe of which is hooked on the woven Dacron® graft of the outlet conduit. To clarify the reliability of measured value, an in vitro test was performed. When a straight tube was used, measured flow by a cuff-type probe was 30% more than the true value which was directly obtained by measuring the overflow volume. Magnetic field across the probe (Nihon-koden FR-type), which we currently use, is not uniformed because of the rectangular situation of positive and negative electrodes. Therefore, a direction of stream line across the probe has a great influence on measured flow. Since we always use a curved outlet conduit, we must take the influence mentioned above into consideration. In our case, the measured flow was 7 to 16% less than the value obtained with a straight tube. In conclusion, the measured flow in our experimental and clinical cases would be 10 to 22% more than the true value. This error might be permissible for clinical usage.
一般社団法人日本人工臓器学会の論文