A new bioelectrical impedance method for measurement of the erythrocyte sedimentation rate.

A new bioelectrical impedance method was developed to determine the erythrocyte sedimentation rate (ESR) by measuring the settling velocity of red blood cells. A sample of blood was collected in a plastic tube with two electrodes, one positioned above the other. Measurements of electrical resistance were made in the upper region of the blood column. As the red blood cells settled towards the bottom of the container, the resistance decreased continuously. The velocity of settling red blood cells was calculated in 45 samples. The values obtained compared favourably with the ESR determined by the standard Westergren method, giving a correlation coefficient of 0.96 and a standard error estimation of 7.0 mmh-1. We conclude that bioelectrical impedance can be used to measure ESR accurately and that this method has important advantages over existing methods.