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Spotlight Case April 2005

Spotlight Case April 2005. Compare and Contrast. Source and Credits. This presentation is based on the April 2005 Spotlight Case in Emergency Medicine See the full article at http://webmm.ahrq.gov CME credit is available through the Web site

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Spotlight Case April 2005

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  1. Spotlight Case April 2005 Compare and Contrast

  2. Source and Credits • This presentation is based on the April 2005 Spotlight Case in Emergency Medicine • See the full article at http://webmm.ahrq.gov • CME credit is available through the Web site • Commentary by: Kerry Cho, MD; Glenn Chertow, MD, MPH, UCSF School of Medicine • Editor, AHRQ WebM&M: Robert Wachter, MD • Spotlight Editor: Tracy Minichiello, MD • Managing Editor: Erin Hartman, MS

  3. Objectives At the conclusion of this educational activity, participants should be able to: • Define contrast nephropathy (CN) • List risk factors for CN • Implement pharmacologic strategies for CN prophylaxis • Follow algorithm for CN risk reduction and prevention

  4. Case: Compare and Contrast A 76-year-old woman came to the emergency department complaining of vomiting, dehydration, and abdominal pain. An abdominal x-ray revealed a pattern consistent with a partial small bowel obstruction. On admission, BUN was 32 mg/dL and creatinine was 1.4 mg/dL. She underwent a contrast-enhanced abdominal CT to look for a lead point in the bowel obstruction.

  5. Contrast Nephropathy (CN) • Definition: an increase of ≥ 0.5 mg/dL or ≥ 25% in serum creatinine concentration within 48 hours following contrast exposure • Calculate baseline renal function • GFR MDRD Calculator for Adults: GFR (ml/min/1.73 m2) = 186 x (PCR)-1.154 x (Age)-0.203 x (0.742 if female) x (1.210 if African American) • Cockcroft-Gault formula: Creatinine Clearance (ml/min) = [(140 - age) * weight (in kg)] / [72 * serum creatinine (mg/dL)] • Multiply by 0.85 if female Levey AS, et al. Ann Intern Med. 1999;130:461-70. Levey AS, et al. Ann Intern Med. 2003;139:137-47.

  6. Risk Factors for CN • Pre-existing chronic kidney disease • GFR/creatinine clearance < 60 mL/min/1.73 m2 considered a risk factor for CN • Diabetes mellitus with proteinuria • Multiple myeloma • Large volume of radiocontrast • Congestive heart failure • Decreased renal perfusion Murphy SW, et al. J Am Soc Nephrol. 2000;11:177-82. Gami AS, et al. Mayo Clin Proc. 2004;79:211-9.

  7. Additional Risk Factors for CN • Older age (with normal kidney function) • Concomitant use of selected drugs • amphotericin B, cyclosporin A, tacrolimus, diuretics, and non-steroidal anti-inflammatory drugs • Proteinuria of any cause • Peri-procedural complications and hypotension

  8. Risk Factors for Contrast Nephropathy Rich MW, Crecelius CA. Arch Intern Med. 1990;150:1237-42.

  9. Case (cont.): Compare and Contrast By hospital day number 3, the patient’s urine output was minimal, and the BUN and creatinine had risen to 70 mg/dL and 3.5 mg/dL, respectively. Her small bowel obstruction continued to improve and no surgical intervention was necessary.

  10. Prevention of Contrast Nephropathy • Avoid contrast • Use ultrasound, MRI • Use small amounts of contrast • Select less toxic radiocontrast agents • Iso-osmolar and low osmolar contrast associated with lower risk of CN • Avoid concomitant use of nephrotoxic agents Barrett BJ, Carlisle EJ. Radiology. 1993;188:171-8. Aspelin P, et al. N Engl J Med. 2003;348:491-9.

  11. Effective strategies N-acetylcysteine Normal saline Sodium bicarbonate Methylxanthines Ineffective strategies Calcium channel blockers Mannitol Furosemide Atrial natriuretic peptide Endothelin antagonists Dopamine Fenoldopam Hemodialysis Pharmacologic Prevention of Nephropathy Ide JM. Invest Radiol. 2004;39:155-70.

  12. N-acetylcysteine for Prevention of CN • Original report found RR of 0.1 of CN with administration of 600 mg BID starting the day prior X 4 doses when compared to placebo • Recent meta-analyses published • Majority show a benefit Tepel M. et al. N Engl J Med. 2000;343:180-4. Nallamothu BK, et al. Am J Med. 2004;117:938-47.

  13. Sodium Bicarbonate for Prevention of CN • Randomized trial of sodium bicarbonate vs normal saline • Baseline creatinine > 1.1mg/dl • Infusion rates were 3 mL/kg/hour for 1 hour before and 1 mL/kg/hour for 6 hours after radiocontrast exposure • N-acetylcysteine not administered Merten GJ, et al. JAMA. 2004;291:2328-34.

  14. Sodium Bicarbonate for Preventionof CN (cont.) • CN defined as a 25% increase in serum creatinine within 2 days of exposure • Incidence of CN: 1.7% in the bicarbonate group vs. 13.6% in the saline group • Low rates of CN subsequently confirmed in open-label study of 191 subjects given a simplified isotonic sodium bicarbonate infusion with radiocontrast exposure Merten GJ, et al. JAMA. 2004;291:2328-34.

  15. Methylxanthine for Prevention of Nephropathy • Recent meta-analysis of theophylline and aminophylline concluded these agents reduce rise in serum creatinine following contrast exposure • Did not report the fraction of patients experiencing > 0.05 increase in serum creatinine, so clinical significance unclear Ix JH, et al. Nephrol Dial Transplant. 2004;19:2747-53.

  16. Case (cont.): Compare and Contrast Due to continued oliguria and persistent uremia hemodialysis was started on hospital day number 5.

  17. Outcome of Contrast Nephropathy • Mortality rates higher • Odds of death increased by a factor of 5.5 in patients with CN • Length of stay (LOS) increased • LOS 6 days vs 1 in patients without CN • Need for dialysis is rare • <1% McCullough PA, et al. Am J Med. 1997;103:368-75. Levy EM, et al. JAMA. 1996;275:1489-94. Aronow HD, et al. Am Heart J. 2001;142:799-805.

  18. Avoiding the Complication • Low-risk patients have a low incidence of nephropathy, 1% or less • Do not need any prophylaxis • Among high risk patients, chronic kidney disease and other risk factors are relative contraindications to radiocontrast exposure • Should receive prophylaxis Maeder et al. J Am Coll Cardiol. 2004;44:1763-71. Waybill et al. J Vasc Interv Radiol. 2001;12:3-9.

  19. Balancing Risk with Benefit • Renal insufficiency and other risk factors are not an absolute contraindication to radiocontrast studies • In one study, elderly patients with chronic kidney disease were half as likely to undergo coronary angiography despite equivalently appropriate clinical indications • Therefore, delaying appropriate testing to administer CN prophylaxis or avoidance contrast studies entirely can be a dangerous strategy Chertow GM, et al. J Am Soc Nephrol. 2004;15:2462-8.

  20. Take-Home Points • Estimate kidney function and risk factors prior to contrast administration • In at-risk patients, consider the urgency of the clinical situation, and the possibility of using non-contrast imaging or delaying imaging to administer prophylactic modalities • Do not delay urgent diagnostic studies, as the delay-associated hazard frequently outweighs the risk of CN

  21. Take-Home Points • If contrast is administered, avoid nephrotoxic medications before and after radiocontrast exposure • The dose of contrast should be minimized, and iso-osmolar contrast material is preferable • Consider nephrology consultation to assist in risk assessment, patient education, and supportive care

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