Cardiac-related changes in lung resistivity as a function of frequency and location obtained from EITS images

Physiological Measurement
P NoppW Wang

Abstract

ECG-gated electrical impedance tomographic spectroscopy (EITS) measurements of the lungs were taken on seven normal subjects in the frequency range 9.6 kHz to 614.4 kHz. The results show that in late systole the resistivity p' relative to the R-wave (i.e. p' = 1 at the R-wave) decreases consistently within the lung. In addition there arises an increase in p' in early systole towards the periphery of the lung. Frequency behaviour of p' changes with location. At all times after the R-wave, in the centre of the lung p' is higher at higher frequency f whereas in the periphery it is lower at higher f. The principal decrease in p' can be explained by increasing pulmonary blood volume due to cardiac contraction. The early systolic increase is presumably due to venous return to the left atrium locally leading blood output from the right ventricle which is delayed by the windkessel effect. Based on a model taking extracapillary and capillary blood volume increase into account, the change in frequency behaviour of p' is explained by regional variations in extracapillary blood vessel size determining the relative contributions of extracapillary blood volume and capillary blood volume change to p' at a certain frequency.

References

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Citations

Apr 16, 1998·Medical & Biological Engineering & Computing·P NoppB H Brown
Apr 23, 2013·Medical Engineering & Physics·Benjamin SanchezRamon Bragos
Dec 31, 2008·Critical Care Medicine·Marc BodensteinKlaus Markstaller
May 27, 2015·Physiological Measurement·Fabian BraunJean-Philippe Thiran
Apr 26, 2012·Physiological Measurement·D T NguyenA L McEwan
Nov 1, 1996·Physiological Measurement·T X ZhaoL Q Lu

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