Changes in the plasma sodium concentration after minor, moderate and major surgery.

The plasma sodium concentration, [Na]P, falls following major surgery and this fall is exacerbated by the administration of sodium-free or sodium-low intravenous fluids in the postoperative period. As a prelude to prospective, but controlled, studies we observed the range of [Na]P on admission for surgery in 477 patients. In 309 patients the extent of the change in [Na]P by the first postoperative day (delta [Na]) was related to the severity of the operation undergone (minor, moderate or major) and the volume of potentially hypo-osmolar intravenous fluid given.

pK1' and bicarbonate concentration in plasma.

Values for pK1' were determined from pH measured at 37 degrees C with three blood-gas analyzers and from calculated pco2 values in 443 freshly separated plasmas, tonometered at 37 degrees C. Plasma was taken from healthy volunteers, seriously ill patients, and hyponatremic patients. pK1' values varied by considerably more than 0.

Changes in plasma solutes after food.

In experiments on 8 healthy young male volunteers, the ingestion of a large meal was found to cause plasma osmolality to rise from 288.8 +/- 0.8 (mean +/- s.

Acute biochemical responses to moderate beer drinking.

The consequences of drinking six pints of beer (3.31) over three hours were investigated in six healthy men. The expected rise in plasma osmolality, fall in plasma vasopressin concentration, and increase in free water clearance occurred; these variables had returned to normal by nine hours.