Evaluation of electronic red blood cell counter.

Abstract

The red blood cell count remains essential for the differential diagnosis of anemia. Extensive degrees of macrocytosis and microcytosis are readily observed in blood smears. Minor, but nevertheless important differences in the sizes of red blood cells may*:Be discovered only by determining the mean corpuscular volume (MCV), as measured by the ratio of the hematocrit reading to the red blood cell count. Inasmuch as the difference between maximal and minimal normal MCV's is only 10 per cent, the red blood cell count should be done with high precision in order to detect minor deviations from normal. A recently designed electronic device seems to provide accurate red blood cell counts, and Avith considerable economy of time. This paper describes (1) the principle of the counter, (2) methods for its use, and (3) the results of evaluation studies performed with the counter. PRINCIPLE AND OPERATION OF ELECTRONIC COUNTER* The electronic counter used in this study is based on the principle that cells are poor electrical conductors, as compared with a saline solution. In operation, a dilute suspension of red blood cells in 0.9 per cent solution of sodium chloride is drawn through a minute aperture conducting an electric current between plati­ num electrodes. Each cell passing through the aperture displaces an equal volume of the solution of electrolyte and thereby modulates the electric current. The resulting pulses are amplified and automatically counted, and they are then