Chapter 28. Acute Renal Injury

See Figures 28-1, 28-2, and 28-3)

Estimation of Glomerular Filtration Rate

• Only valid in a stable situation, that is, not while in ARF
• If ARF, measure clearance; a 2-hour clearance is as good as a 24-hour measurement

Modification of Diet in Renal Disease Study (MDRD) Group formula:

Estimated creatinine clearance

Cockroft–Gault formula:

Estimated creatinine clearance (mL/min)

Preoperative Evaluation

• Estimate creatinine clearance:
  • Using either Cockroft–Gault or MDRD formula
• Acute or chronic?
  • Previous serum creatinine values
  • Sudden rise?
• Causes:
  • Low perfusion:
    • Cardiogenic shock
    • Sepsis and infection
    • Hypovolemia
  • Nephrotoxic insults:
    • Radiocontrast
    • Aminoglycosides
    • Calcineurin inhibitors (tacrolimus/FK-506 or cyclosporine)
  • Other causes
  • Urinary tract infections
  • Postrenal obstruction

Preoperative Management

• Consider maintenance fluid while NPO
• Consider preventive strategies especially for radiographic procedures: no strategy has however been proven to be effective (see below):
  • Sodium bicarbonate
  • N-Acetylcysteine

Intraoperative Management

• Consider invasive monitoring: urine output not necessarily reliable indicator of adequate perfusion:
  • Pulmonary artery catheter
  • Intraoperative transesophageal echocardiography
• Diligent fluid management:
  • Fluid deficit and maintenance and blood loss
  • Lactated Ringer will cause less acidosis (and hyperkalemia) than normal saline
• Avoid further insults:
  • Minimize amount of (low osmolar) radiocontrast
  • Avoid hypotension: maintain BP near baseline (not “normal”) BP
• With marginal renal function/anticipated large blood loss and possibility for hyperkalemia:
  • Frequent monitoring of potassium and pH
  • Prepare insulin/glucose
  • Maintain adequate calcium levels
  • Consider intraoperative continuous venovenous hemodialysis (CVVHD)