ELECTRICAL-IMPEDANCE ALTERATIONS OF RED-BLOOD-CELLS DURING STORAGE

The electrical impedance of blood is determined mainly by the resistan ce of the plasma (R(p)), resistance of the red cell interior fluid (R( i)), and capacitance of the cell membranes (C-m). These parameters wer e measured on 10 stored blood samples consecutively during 4 or 5 week s of storage at 4 degrees C, once every week. Compared to the values o f fresh samples, a statistically significant decrease in R(p) was foun d mainly during the first week of storage, R(i) did not decrease signi ficantly until after 3 weeks, whereas C-m decreased progressively with time. These alterations can be explained by known red cell lesions du ring storage. The results indicate that electrical impedance measureme nts might be useful for monitoring red cell ageing and assessing the q uality of stored red blood cells.