Abstract
23 studies were made in 13 patients with edema to discover the time required for the attainment of equilibrium distr. for CNS in the body of edematous patients after the intraven. inj. of NaCNS. The CNS concs. of sera and transudates drawn simultaneously at varying times after the inj. of NaCNS were measured. Diffusion equilibrium usually was not attained until 6-10 hrs. after the inj. of NaCNS. This finding was contrasted with the observation that diffusion equilibrium for CNS obtains in normal subjects within 1 hr. after the inj. of NaCNS. In routine studies of the amt. of "available fluid" for CNS distr. in edematous patients, 12 to 24 hrs. should elapse between the adm. of the CNS and the drawing of blood for measurement of the CNS conc. in the serum. In all studies of the distr. of substances at equilibrium between plasma and transudates in edematous patients, the relatively long time required for the attainment of diffusion equilibrium must receive consideration.