KIDNEY DISEASE

Approximately 1% of patients suffer a significant reduction in kidney function after major surgery. The risk is much higher, however, in patients undergoing cardiac operations, where 10–30% of patients develop acute kidney injury. The development of acute kidney injury is an independent predictor of mortality, even if renal dysfunction resolves. The mortality associated with the development of perioperative acute kidney injury that requires dialysis exceeds 50%. Risk factors associated with postoperative deterioration in kidney function are shown in Table 3–8. Several medications, including “renal dose” dopamine, mannitol, N-acetylcysteine, and furosemide, have been evaluated in an attempt to preserve kidney function during the perioperative period. None of these have proved effective in clinical trials and generally should not be used for this indication. Maintenance of adequate intravascular volume is likely to be the most effective method to reduce the  risk of perioperative deterioration in kidney function. Exposure to renal toxic agents such as nonsteroidal anti-inflammatory drugs and intravenous contrast should be minimized or avoided. Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers reduce renal perfusion and may increase the risk of perioperative acute kidney injury. Although firm evidence is lacking, it may be useful to temporarily discontinue these medications in patients at risk for perioperative acute kidney injury.

Although the mortality rate for elective major surgery is low (1–4%) in patients with dialysis-dependent chronic kidney disease, the risk for perioperative complications, including postoperative hyperkalemia, pneumonia, fluid overload, and bleeding, is substantially increased. Postoperative hyperkalemia requiring emergent hemodialysis has been reported to occur in 20–30% of patients. Patients should undergo dialysis preoperatively within 24 hours before surgery, and their serum electrolyte levels should be measured just prior to surgery and monitored closely during the postoperative period.