Abstract
Blood volume was determined with both T-1824 (Evans blue) and carbon monoxide (CO) for 2 young women, 2 young men, and 2 men ages 70 and 75. In the CO method a precise volume of CO was administered from a closed system, and the CO concentrations in blood were determined on the Van Slyke-Neill apparatus before and at the end of a 10-min. rebreathing period. The manometric technic is presented in detail and possible sources of errors are discussed. Comparisons were made during the spring in Indiana, in the hot desert, and at an altitude of 3800 m. Blood volume was taken as the sum of plasma volume (by T-1824 method) and red cell volume (by CO method); from these values body hematocrit was calculated. The ratios of body hematocrit to observed hematocrit ranged from 0.89 to 1.05 in 16 observations, with a median value of 0.93. In 12 of the 16, they ranged from 0.89 to 0.95, also with a median value of 0.93. Blood volumes determined by the CO method, using the 0.93 ratio, were within -1 to +4% of the blood volumes as determined above in 12 of 16 subjects. The other four differed by -7 to -13%.