Perioperative renal, fluid, and electrolyte management.

Normal physiologic changes of aging increase the likelihood of renal-electrolyte disorders in the elderly surgical patient. The most important of these changes are a decrease in the GFR, decreased urinary concentrating ability, and narrowed limits for the excretion of water, sodium, potassium, and acid. Because of the decrease in GFR, the elderly surgical patient is at increased risk for virtually every cause of acute renal failure, an outcome associated with a mortality of greater than 50%. Certain types of surgery, especially cardiac, aortic, and biliary tract operations, are associated with a higher risk of acute renal failure than are others. The most important principles of prevention in the elderly surgical patient are to maintain normal intravascular volume and avoid hypovolemia. Meticulous attention must be paid to salt and water balance and to drug dosing. Should perioperative renal insufficiency occur, evaluation and management in the elderly patient are similar to usual practices in a younger individual.