Acute Renal Failure: Only three possible causes: • Inadequate perfusion • Intrinsic renal damage • Obstruction to the outflow of urine
Is Renal Failure Acute or Chronic? • History: Get the old records • Take a history: • Longstanding or progressive symptoms? • Underlying illnesses? • Medications, including OTC meds? • Prior MD encounters or laboratory work? • Physical examination: • Does the patient appear chronically ill? • Volume status? • Diabetic retinopathy? • Ultrasound • Laboratory data: • Anemia • Creatinine level?
Acute Renal Failure: • Always rule out obstruction. • Pre-renal vs. intrinsic damage. • Urine sodium, FENa • Urine sediment • Caveats: • Contrast nephropathy • Pigment nephropathy • Heart failure • Liver failure
Genesis of Acute Tubular Necrosis • Tubular obstruction by debris • Backleak across damaged epithelium • Proximal tubular damage leading to increased delivery to the macular densa with consequent reduction in GFR mediated by GT feedback.
Acute Renal Failure: Most Common Causes at PHD • Sepsis • Post-surgical (AAA, CABG) • Rhabdomyolysis • Drugs: • Contrast • NSAIDs • Illicit/suicidal • All of the above
Acute Tubular Necrosis: Reversing the Process or Speeding Recovery? • Diuretics • Atrial natriuretic peptide • Low dose dopamine • Fenoldapam • Volume
Anaritide in acute tubular necrosis. Auriculin Anaritide Acute Renal Failure Study Group The administration of anaritide did not improve the overall rate of dialysis-free survival in critically ill patients with acute tubular necrosis. However, anaritide may improve dialysis-free survival in patients with oliguria and may worsen it in patients without oliguria who have acute tubular necrosis. (Allgren RL; Marbury TC; Rahman SN; Weisberg LS; Fenves AZ; Lafayette RA; Sweet RM; Genter FC; Kurnik BR; Conger JD; Sayegh MH: N Engl J Med 1997 Mar 20;336(12):828-34)
Low-dose dopamine in patients with early renal dysfunction: a placebo-controlled randomised trial. Australian and New Zealand Intensive Care Socity (ANZICS) Clinical Trials Group Administration of low-dose dopamine by continuous intravenous infusion to critically ill patients at risk of renal failure does not confer clinically significant protection from renal dysfunction. (Bellomo R; Chapman M; Finfer S; Hickling K; Myburgh J; Lancet 2000 Dec 23-30;356(9248):2139-43)
Multicenter clinical trial of recombinant human insulin-like growth factor I in patients with acute renal failure. rhIGF-I does not accelerate the recovery of renal function in ARF patients with substantial comorbidity. (Hirschberg R; Kopple J; Lipsett P; Benjamin E; Minei J; Albertson T; Munger M; Metzler M; Zaloga G: Murray M; Lowry S; Conger J; McKeown W; O’shea M; Baughman R; Wood K; Haupt M; Kaiser R; Simms H; Warnock D; Summer W; Hintz R; Myers B; Haenftling K; Capra W; et al; Kidney Int 1999 Jun; 55(6):2423-32)
Acute Tubular Necrosis: Reversing the Process or Speeding Recovery: • Once the insult has occurred, no pharmacologic intervention has been demonstrated to be of any benefit.
Acute Tubular Necrosis: Treatment • Optimize volume • Physical examination • Chest xray • Hemodynamic measurements? • Stop potential nephrotoxins; avoid repeated insults • Dye studies • Surgery • NSAIDs
Question: • Acute renal failure occurs on day 1 with a creatinine of 1.2. • On day 3, creatinine is 3.2. • On day 6, creatinine is 7.0 • Renal function is: • getting better? • unchanged? • getting worse?
Question: • Acute renal failure occurs on day one when a patient’s sole remaining kidney is removed for malignancy. Creatinine is 1.2. • On day 3, creatinine is 3.2. • On day 7, creatinine is 7.0. • Renal function is: • getting better? • staying the same? • getting worse?
Acute Tubular Necrosis: Treatment • Check the MAR daily for inappropriate drugs or wrong dosages. Do not depend on pharmacy alerts. • Avoid hypotension and overzealous short-term blood pressure management. • Watch potassium. • Meticulous general medical care. • nursing • line changes • Nutritional support? • Enteral if feasible • Little evidence supporting benefit of TPN in an illness of less than two weeks • If nutritional therapy is initiated, 1.5 gm/kg of protein
Acute Tubular Necrosis: Dialysis • When? • Volume status and electrolytes • Etiology and anticipated course • urine output • Risk • Biocompatible membranes • Hemodialysis vs. CVVHD • Is more better?
Acute Tubular Necrosis: Outcome • ICU mortality = 50%
Acute Tubular Necrosis: Prevention • Adequate volume status prior to an anticipated insult. • Drugs: • NSAIDs • IV contrast • minimize dosage • avoid multiple sequential doses • avoid concomitant or recent NSAIDs • Newer agents • mucomyst • fenoldapam • Delay surgical procedures after a possible insult. • Avoid the second hit.
Acute Tubular Necrosis: • ref: Diagnosis and Treatment of Acute Tubular Necrosis. Essen ML, and Schrier RW, Annals of Internal Medicine 137:744, 5Nov02.