Non-radioisotopic estimate of extracellular volume during isotonic expansion in anuric dogs.

In six anuric dogs infused in two steps with isonatremic (= having the same sodium concentration as each dog's initial extracellular space) sodium chloride solutions, stable chloride space was computed by mass conservation and was compared to radiosulphate space. There was close agreement between estimates of preinfusion extracellular volume by radiosulphate and stable chloride spaces. Computed increases in radiosulphate and stable chloride spaces agreed with the infused volumes in each step.