The Mechanism of Acidosis Produced by Hyperosmotic Infusions.

It has been known for many years that the administration of large loads of sodium chloride, either orally (2) or by infusion of isotonic (3, 4) or hypertonic (5-10) saline produces a disturbance in acid-base equilibrium of the blood as evidenced by a fall in total carbon dioxide content of the plasma or implied by a fall in the difference between the concentrations of sodium and chloride in the plasma. In the relatively few instances in which blood pH has been recorded, acid values have been found (4, 8, 10). The mechanism of the acidosis produced by a load of sodium chloride has received only scant attention. Peters and Van Slyke (11 ) commented that the acidosis must in part be due to dilution of the blood. Shires and Holman (4) adopted a similar viewpoint and coined the term "dilution acidosis." They pointed out that whereas dilution of a bicarbonate-buffered solution in vitro with saline would not produce a fall in pH, dilution of the extracellular fluid in vivo with isotonic saline would, for with continuing production of carbon dioxide, the dilution would affect only the bicarbonate concentration. Presumably after administration of hypertonic saline, dilution of extracellular bicarbonate occurs because water is osmotically shifted from the intracellular compartment. If there were no change in Pco,, extracellular pH would fall providing the