Simultaneous Determinations of the Total Volume of Red Blood Cells by Use of Carbon Monoxide and Chromium51 IN HEALTHY AND DISEASED HUMAN SUBJECTS1

Abstract

In 35 human subjects, 6 healthy and 29 with various diseases, simultaneous measurements were made of the apparent volume of red cells, using CO gas and cells tagged with Cr51. The method of Sterling and Gray for determining Cr51 space was modified slightly in measuring CO space; a closed re-breathing system and analysis based on PdCl2 reduction were used. Using blood samples taken 20 minutes after delivery of CO and of radioactively tagged cells, the volume of red blood cells was consistently larger by the CO than by the Cr51 method, the average difference amounting to 16% of the Cr51 value. Since previous experiments had shown that blood levels of CO are constant after 20 minutes of re-breathing, it was concluded that significant quantities of CO leave the blood stream during the first 20 minutes after delivering the gas and become fixed at unknown extravascular sites.