Impedance spectroscopy on living tissue for determination of the state of organs

During ischemia, organ tissue undergoes alterations rendering finally a resuscitation impossible. Accumulation of metabolic products, cell swelling caused by osmosis and closing gap junctions are important effects which can be detected by means of electrical impedance spectroscopy: at high frequencies (> 1 MHz) the total content of ions in the tissue can be ascertained, at low frequencies (< 1 kHz) the narrowing of the extracellular pathways (caused by cell swelling) and the state of the gap junctions. These changes are demonstrated in a canine heart muscle and a porcine liver. A pronounced effect is the steep increase in impedance at low frequencies, a common feature in organs whose cells are interconnected by gap junctions. Closing gap junctions indicates the limit of viability, long before cell membranes disintegrate. The impedance spectroscopy method is rapid and innocuous to the tissue. In the future it may be of use in surgery, especially in transplantation. (C) 1998 Elsevier Science S.A. All rights reserved.