PLASMAVOLUMECHANGESFOLLOWINGTHE ADMINISTRA- TION OF ALBUMIN TO PATIENTS WITH THE NEPHROTICSYNDROME

In the course of a study of patients with the nephrotic syndrome, data have been obtained on the changes of plasma volume which followed the intravenous administration of concentrated human plasma albumin. These data are presented here together with a thermodynamic formulation of the Starling hypothesis and a brief discussion of the mechanism of action of albumin. According to the Starling hypothesis, four major factors are involved in the regulation of the net movement of water across the capillary walls which separate the plasma and interstitial fluid compartments. The factors are the hydrostatic pressures in the capillaries and in the interstitial fluid and the so-called colloid osmotic pressures of plasma and of interstitial fluid. Variations of one or more of these factors may determine a net movement of water and a change in the respective volumes of the two compartments. The problem is essentially that of membrane equilibria and of disturbances of these equilibria. Membrane equilibria with respect to water are most simply described in terms of the chemical potential of water in each of the two compartments and in terms of the factors which affect the chemical potential of water (see, for example [I] ). Let the chemical potential of water be greater in one compartment of a two compartment system than in the other compartment. Then, provided a path is available there will be net movement of water from the compartment where the chemical potential of water is higher to the compartment where the chemical potential of water is lower. The two compartments in the system under consideration are the plasma and interstitial fluid; their volumes are denoted by V" and V', respectively. The difference of the 1Present Address: The Johns Hopkins School of Medicine, Baltimore, Md. 2 Present Address: Cornell University Medical College, New York, N. Y. chemical potentials of water in the two compartments is: