Estimation of cardiac output by bioimpedance cardiography

Changes in thoracic electrical bioimpedance during the cardiac cycle have been related to the ejection of the stroke volume of blood during cardiac systole. Refinements in the recording and analysis of these changes permit estimation of cardiac output. Encouraging reports comparing results obtained by this method and those obtained simultaneously using the current standard invasive method have been published. While there are limitations, the advantages of this technique are sufficient to make bioimpedance cardiography attractive to the military physician. It is for these reasons that the principles of this technology are reviewed in this paper.