Abstract
Measurement of lung water is an important diagnostic means of assessing pulmonary oedema. Water content affects the dielectric spectrum at microwave frequencies, but quantification is still a problem. A new lung tissue model is presented that allows the calculation of water content from dielectric permitivity. The dielectric permitivity of lung tissue was measured by microwave reflectometry using a noninvasine surface probe. During perfusion of rat lungs (n=22) with blood, injury was induced by interruption of the blood supply for a duration between 0 (control) and 2h. Water content was assessed from dielectric permitivity using a new mixture formula and was also determined by drying and weighing. The mixture formula allows for the dielectric polarisation of water, dry matter and air in the tissue. A linear correlation was found between total water content determined from dielectric permitivity and that from drying and weighing (y=1.001x, R2=0.8). Lung injury showed an increase in total water content from 80.9±1.2% (control) to 84.1±0.9% (p<0.01). The analysis of dielectric permitivity data at microwave frequencies with the new tissue model is sensitive enough to detect water accumulation produced by lung injury and it can be used to monitor total water content without tissue destruction.
Similar content being viewed by others
References
Böttcher, C. J. F., andBordeweijk, P. (1978): ‘Theory of electric polarisation’ (Elsevier, Amsterdam, 1978)
Brown, B. H., Primhak, R. A., Smallwood, R. H., Milnes, P., Narracott, A. J., andJackson, M. J. (2002a): ‘Neonatal lungs —can absolute lung resistivity be determined non-invasively?’,Med. Biol. Eng. Comput.,40, pp. 388–394
Brown, B. H., Primhak, R. A., Smallwood, R. H., Milnes, P., Narracott, A. J., andJackson, M. J. (2002b): ‘Neonatal lungs: maturational changes in lung resistivity spectra’,Med. Biol. Eng. Comput.,40, pp. 506–511
Demling, R. H., Lalonde, C., andIkegami, K. (1993): ‘Pulmunary edema: pathophysiology, methods of measurement, and clinical importance in acute respiratory failure’,New Horiz.,1, pp. 371–380
Foster, K. R., andSchwan, H. P. (1989): ‘Dielectric properties of tissues and biological materials: a critical review’,Crit. Rev. Biomed. Eng.,17, pp. 25–104
Genoni, M., Biraima, A. M., Bode, B., Shan, A. C., Wilkler, M. B., andTurina, M. I. (2001): ‘Combined resection and adjuvant therapy improves prognosis of sarcomas of the pulmonary trunk’,Cardiovasc. Surg.,42, pp. 829–833
Iskander, M. F., andDurney, C. H. (1983): ‘Microwave methods of measuring changes in lung water’,J. Microwave Power,18, pp. 265–275
Kaatze, U., andUhlendorf, V. (1981): ‘Dielectric properties of water at microwave frequencies’,Z. Phys. Chem.,126, pp. 152–165
Lange, N. R., andSchuster, D. P. (1999): ‘The measurement of lung water’,Crit. Care,3, pp. R19-R24
Miura, N., Shioya, S., Kurita, D., Shigematsu, T., andMashimo, S. (1999): ‘Time domain reflectometry: measurement of free water in normal lung and pulmonary edema’,Am. J. Physiol.,276, pp.:207-L212
Novick, R. J., Gehman, K. E., Ali, I. S., andLee, J. (1996): ‘Lung preservation: the importance of endothelial and alveolar type II cell integrity’,Ann. Thorac. Surg.,62, pp. 302–314
Nowak, K., Kammler, M., Bock, M., Motsch, J., Hagl, S., Jacob, H., andGebhard, M. M. (2002): ‘Bronchial artery revascularization affects graft recovery after lung transplantation’,Am. J. Respir. Crit. Care. Med.,165, pp. 216–220
Rigaud, B., Morucci, J.-P., andChauveau, N. (1996): ‘Bioelectrical impedance techniques in medicine’,Crit. Rev. Biomed. Eng.,24, pp. 257–351
Sakka, S. G., Klein, M., Reinhart, K., andMeier-Hellmann, A. (2002): ‘Prognostic value of extravascular lung water in critically ill patients’,Chest,122, pp. 2080–2086
Schaefer, M., Gross, W., Ackemann, J., andGebhard, M. M. (2002): ‘The complex dielectric spectrum of heart tissue during ischemia’,Bioelectrochemistry,58, pp. 171–180
Schaefer, M., Gross, W., Preuss, M., Ackemann, J., andGebhard, M. M. (2003): ‘Monitoring of water content and water distribution in ischemic hearts’,Bioelectrochemistry,61, pp. 85–92
Schwan, H. P. (1957): ‘Electrical properties of tissues and cell suspensions’,Adv. Biol. Med. Phys.,5, pp. 147–209
Sibbald, W. J., Warshawski, F. J., Short, A. K., Harris, J., Lefcoe, M. S., andHolliday, R. L. (1983): ‘Clinical studies of measuring extravascular lung water by the thermal dye technique in critically ill patients’,Chest,83, pp. 725–731
Sivak, E. D., Starr, N. J., Graves, J. W., Cosgrove, D. M., Borsh, J., andEstafanous, F. G. (1982): ‘Extravascular lung water values in patients undergoing coronary artery bypass surgery’,Crit. Care Med.,10, pp. 593–596
Staub, N. C. (1983): ‘The measurement of lung water content’,J. Microwave Power,18, pp. 259–263
Ware, L. B., andMatthay, M. A. (2000): ‘The acute respiratory distress syndrome?’,N. Engl. J. Med.,342, pp. 1334–1349
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Schaefer, M., Nowak, K., Kherad, B. et al. Monitoring water content of rat lung tissuein vivo using microwave reflectometry. Med. Biol. Eng. Comput. 42, 577–580 (2004). https://doi.org/10.1007/BF02347537
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF02347537