Abstract
A new system for continuous monitoring of hematocrit during extracorporeal circulation was developed. The system utilizes the principle that the ratio of blood resistivity to plasma is a function of hematocrit. Blood-plasma was continuously separated from blood by a disk filter type plasma separator installed on a housing wall of a non-positive displacement type blood pump and its resistivity was simultaniously measured with blood by a resistivity meter. Hematocrit was calculated from the ratio using the Maxwell-Fricke expression. The hematocrit values measured by this system (Hctc) were compared with those by the capillary method (Hctm): the linear regression equation was Hctc=1.00Hctm-0.002 with a correlation coefficient r=0.996. Close agreement between the simultaleous data from these two methods were also observed in animal experiments using dogs.
