| Project/Area Number |
63570408
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Circulatory organs internal medicine
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| Research Institution | Nagoya City University Medical School |
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Principal Investigator |
FUJINAMI Takao Nagoya City University Medical School, Third Department of Medicine, Professor, 医学部・第三内科学教室, 教授 (60080024)
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| Co-Investigator(Kenkyū-buntansha) |
堀江 健司 名古屋市立大学, 医学部・第三内科学教室, 研究員
家田 幸一 名古屋市立大学, 医学部・第三内科学教室, 研究員
HAYANO Junichiro Nagoya City University Medical School, Third Department of Medicine, Associate, 医学部・第三内科学教室, 助手 (90173054)
OKUDA Noriaki Nagoya City University Medical School, Third Department of Medicine, Instructor, 医学部・第三内科学教室, 講師 (20112500)
馮 守道 名古屋市立大学, 医学部第三内科学教室, 研究員
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| Project Period (FY) |
1988 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1989: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1988: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Bio-electric impedance method / Aortic blood flow / Water volume in tissue / atherosclerosis obliterance / Lung congestion / Pulmonary edema / Pulmonary extravascular water volume / Frequency variation on bio-electrical impedance / 生体電気インピーダンス / インピーダンス・カルジオグラフィー / 細胞外液 / 細胞内液 / 動脈血流 / 可変周波数 / 無侵襲計測法 |
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| Research Abstract |
When a constant high frequency alternative electric current is passed through the thorax, voltage change detected from the chest refers to the thoracic electrical property. Bioelectrical impedance is obtained as the ratio of voltage to alternative electrical current. From the thoracic impedance change, Kubicek has introduced impedance cardiography to estimate stroke volume non-invasively. Present studies are intended to expand clinical application of the thoracic bio-electrical impedance method to obtain more informations on the circulation. Following results were obtained.
1) To eliminate impedance change by respiration, we have recorded the thoracic impedance change (DELTA Z) without holding respiration to a data recorder, then DELTA Z data was digitalized by A-D converter, and respiratory fluctuation of DELTA Z was obtained by cubic spline interpolation. By subtraction of respiratory DELTA Z change from original DELTA Z, new DELTA Z wave without respiration change was obtained.
2) To
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detect aortic flow selectively by bio-electrical impedance changes, the electrodes were positioned at the point of V_8 of ECG and of second thoracic vertebra on the posterior median line. By this lead system, height of the first derivative of impedance change (dZ/dt) wave was correlated with the aortic flow velocity obtained by the catheter tip velocity transducer (r= 0.84). This result indicates that the impedance change of this system reflects aortic flow. An index of the aortic compliance was calculated from division of amplitude of the impedance change (DELTA Z) by pulse pressure. This index(Y) was correated with volume elasticity(X) obtained, from RI angiography by equation of Y = 124.52 X100/X + 4.52 (r = 0.78, P<0.001).
3) Ratio of aortic flow and lower leg determined with bioelectric impedance method was valuable for diagnosis of arteriosclerosis obliterance (ASO).
4) Using frequency variable impedance analyzer, tissue fluid changes in the leg during pregnancy were studied. Lower frequency of applied current may pass through extra-cellular fluid, and high frequency of the current may pass both extra- and intra- cellular fluid. We used 12 steps of frequency from 2 kHz to 300 kHz for the study and estimated resistance of extracellular fluid (Re) and of intra cellular fluid (Ri) from a locus of admittance. An apparent increase in Re during the mid term of pregnancy was observed.
5) Determination of water content in the thorax to estimate degree of lung congestion (congestive heart failure) was intended. The thorax was considered as truncated cone model and mean thoracic impedance (rho chest) was calculated from basal thoracic impedance (Zo) of Kubicek's impedance cardiography with variable frequency from 2 kHz to 200 kHz. The highest rho chest value was obtained at the frequency of 10 KHz. and significantly low rho chest value in the patients with pulmonary edema as compared with the healthy control subjects.
Although, it is considered that the applied electric current does not distribute equally through the lung, we used an experimental model with one of the electrode in the central vein and the other on the surface of the thorax. Experimental model of congestive heart failure was induced in rabbits by infusion of 70% dextran solution and bio-electrical impedance was determined between an electrode in the central vein and combined electrode at the neck and lower thoracic. Pulmonary extravascular water volume was determined by the method of Pearce and Yamashita on desiccated lung at the end of the experiment. Impedance at 10 kHz of applied electric current was significantly correlated with PEWV (r= 0.87) and central venous pressure (r=0.93) Application for human study is under consideration. Less
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