Changes in electrical and physiological properties of human blood during storage.

In this study, the relationship between physiological parameters and electrical impedance changes of human blood and their further clinical implications are investigated. The study is performed on 255 erythrocyte suspension samples derived from 51 male donors. The samples are stored at 4&#176;C and measurements are done on the 0^th, 10^th, 21^st, 35^thand 42^nddays of storage. The complex impedance is measured in the frequency range from 100 kHz to 1 MHz. The extracellular resistance R<inf>e</inf>and the effective cell memebrane capacitance C<inf>m</inf>increased progressively with storage time while the intracellular resistance R<inf>i</inf>has decreased. Electrical impedance alterations are explained in terms of the measurements of Na⁺, K⁺and Cl^-concentrations, pH and ATP. Storage of red blood cells resulted in a rise in the extracellular K⁺and a fall in the extracellular Na⁺, Cl^-, pH and ATP. Variance analysis (ANOVA) is used to evaluate any variations in blood parameters, in relation to storage time. According to the (SPSS) regression analysis, R<inf>i</inf>and R<inf>e</inf>are highly correlated with Na⁺, K⁺, Cl^-and pH and, more significantly with ATP. The Cole-Cole parameters F<inf>c</inf>and &#945; showed very little change with storage time and C<inf>m</inf>had weak correlations with blood parameters. Results show that complex impedance measurements may serve as a useful indicator in the quality assessment of blood bank stored blood samples.