Management of Fluid and Electrolyte Problems

Abstract

Summary A variety of factors dictate fluid and electrolyte therapy in the postoperative period. Fundamental to provision of therapy is a knowledge of body composition. Although sodium is the major extracellular ion, it is important to recognize that potassium is the major intracellular ion and to a degree, more prevalent on a whole body basis than sodium. The distribution of total body water between the two major fluid spaces (intracellular fluid as well as extracellular fluid) change during stress conditions, and fluid resuscitation therapy requires a clear-cut understanding of the changes that occur. A common problem in the postoperative patient is control of serum sodium. In this regard it is important to recognize that serum sodium is related to both total body sodium as well as total body potassium divided by total body water. Thus, changes in potassium will result in changes of serum sodium. Factors that modify fluid and electrolyte requirements inelude gastrointestinal losses, insensible water loss, pre-existing deficits due to chronic diarrhetic therapy, mechanical ventilation, hyperthyroidism, and the type of anesthetic technique employed.