title: Origin of the impedance cardiogram investigated in the dog by exchange transfusion with a stroma-free haemoglobin solution.
abstract: In an anaesthetized dog an exchange transfusion was carried out with stroma-free haemoglobin solution. The total circulating blood volume was kept constant. The heart-syncronous changes in the thoracic electrical impedance (Zo) were measured before and after the exchange transfusion. Zo consists of a parallel connection of a tissue impedance (Zt) and a blood impedance (Zb). With the aid of this model for Zo the relative variations in Zb (delta Zb/Zb) were calculated from the relative variations in Zo (delta Zo/Zo). The marked decrease of delta Zb/Zb during the experiment can only be explained by the fact that apart from the heart-synchronous changes in vascular volume the impedance changes are also caused by flow dependent changes in the electrical conductivity of blood caused by variations in orientation of the erythrocytes.
mesh_terms: D000818:Animals; D001810:Blood Volume; D004285:Dogs; D004553:Electric Conductivity; D004912:Erythrocytes / Q000502:physiology*; D005078:Exchange Transfusion, Whole Blood; D006400:Hematocrit; D006439:Hemodynamics; D006454:Hemoglobins; D012212:Rheology
chemical_list: D006454:Hemoglobins