Plasma volume estimation in severely ill infants and children using a simplified Evans blue method.

Plasma volume was measured using Evans blue dye and 125iodinated human serum albumin (RIHSA) simultaneously in order to evaluate the accuracy of a simplified Evans blue method recommended by Nielsen and Nielsen (1962). 9 studies were performed in 8 newborn infants weighing 1.07 to 2.85 kg and 16 studies in 14 patients aged 6 months to 14 years suffering from severe circulatory disturbances. In 20 studies, plasma volumes measured by Evans blue and by RIHSA agreed within +/-5%, and in all the studies within +/-10%. The Evans blue method yielded higher plasma volumes than the RIHSA method in 19 instances. The mean difference (paired t-test) was only significant in newborn infants (+4.0+/-3.6%; P less than 0.05). The disappearance rates of Evans blue exceeded that of RIHSA in 16 studies, but this was only significant in the patients older than 6 months (+2.3+/-4.2%/h; P less than 0.05).