Considerations of postoperative electrolyte and fluid replacement.

The most important postoperative fluid considerations are maintenance of adequate urinary output, of blood volume, and of extracellular and interstitial cell water and electrolytes. Normal urinary output is between 1,000 and 1,500 cc. daily. A fluid intake of 2,000 cc. of 5 per cent dextrose in distilled water, plus 500 cc. of normal saline solution, will insure this amount of urinary output. The use of 5 per cent dextrose solutions in distilled water provides fluid, retards the protein catabolism of the body, and spares electrolytes. Irradiated plasma is the only intravenous solution which will adequately supply protein in amounts to maintain nitrogen equilibrium. Protein hydrolysates in the absence of adequate caloric intake do not provide enough protein for nitrogen balance. The role of the potassium ion is ordinarily not a consideration in postoperative fluid management. It becomes a consideration in the presence of a large amount of drainage from wounds or abscess cavities, nasogastric suction, or intestinal fistulae. It also must be given attention in cases in which parenteral administration of fluids is necessary for a prolonged period.