Analysis and interpretation of the impedance blood coagulation curve.

The impedance coagulation curve represents the relationship between the changing impedance of a clotting blood sample and the impedance of a heparinized control sample. The impedance method is independent of the conventional technics for coagulation studies and offers, therefore, new perspective into the study of the coagulation process. The technic provides accurate measures of the whole-blood clotting time and clot retraction time and has higher diagnostic power than current methods for whole-blood clotting time determination. The purpose of this study was to reveal the mechanism of the impedance changes and to explore the curve for additional information relevant to clinical or theoretical problems. It is established that before clotting the curve reflects "lag" and "activation" phases that strongly suggest a "cascade mechanism" of coagulation activation. The mechanisms of other parts of the curve are explained and their possible relevances to the coagulation process are discussed.