Rebellion21: Kidneys and Contrast

In this 10 minute lecture from Rebellion in EM 2021, I discuss the literature, both old and new, on IV contrast and the risk of post-contrast acute kidney injury.

Old News:

• Flaws in the assumption that contrast itself caused AKI
• Data on this topic is far from high quality: Observational data, no RCTs
  • Creates selection bias based on the fact that patients with elevated renal function most likely did not receive IV contrast
  • Makes it impossible to tell the difference between contrast induced vs associated injury
• Confounding bias (Is it the contrast or maybe large volumes of 0.9% saline, or nephrotoxic medications given prior, or just the disease process itself)
• What outcome are we actually talking about?
  • Rise in Cr vs clinically relevant outcome like renal failure, dialysis, death

Is Contrast the Devil?

• Actually, contrast is an easy culprit
  • “Lazy diagnosis” – easy to blame
• There are other risk factors to consider
  • HTN, DM, diuretic use, dehydration
  • Nephrotoxic medications
  • Large volumes of unbalanced crystalloids
• Contrast we use today is different from contrast many years ago
  • High-osmolar in the past, not used any more
• IV vs IA also makes a difference:
  • Risk seems to be higher with intra-arterial administration (e.g., coronary angiography) vs intravenous

Newer Perspective:

• 4 trials from 2017 & 2019 with ≈130k patients
  • No difference in AKI, CKD, HD, or Mortality
• Radiology literature has 5 studies from 2013 – 2015 with ≈80k patients
  • Also No difference in AKI, CKD, HD, or Mortality
• ACR-NKF Consensus Statement from January 2020: “The risk of acute kidney injury (AKI) developing in patients with reduced kidney function following exposure to intravenous iodinated contrast media has been overstated.”

Why is there Controversy?

• Shades of gray – still some scenarios where we don’t know the answer
  • Renal transplant
  • Serum Cr ≥4.0mg/dL
  • eGFR<30mL/min/1.73m2
• We’re all looking at different literature – nephrology vs EM vs radiology vs IM
• If someone has a certain comfort level with a medical decision, and now they’re learning a different way, it can cause anxiety / resistance
• Most hospitals have protocols in place that involve multiple specialties, but most of the time these people don’t actually come together to change those protocols based on the evidence
• It requires more effort and more work to come together – and so people don’t do it

If you Remember Nothing Else:

• Even per ACR/NKF consensus statement, “If contrast media administration is required for a life-threatening diagnosis, then it should not be withheld based on kidney function” — even in CKD stages 4 or 5.
• Consider interdisciplinary discussions in your own workplace to bring everyone to the table
• Assess why we need the contrast (e.g., life-threatening cause of abdominal pain vs years of chronic abdominal pain)
• In acute situations “Life over kidney”

References:

1. American College of Radiology Manual on Contrast Media 2021 [Link is HERE]
2. Biondi-Zoccai G et al. Nephropathy After Administration of Iso-Osmolar and Low Osmolar Contrast Media: Evidence from a Network Meta-Analysis. Int J Cardiol 2014. PMID: 24502883
3. Davenport MS et al. Contrast Material-Induced Nephrotoxicity and Intravenous Low-Osmolality Iodinated Contrast Material. Radiology 2013. PMID: 23360737
4. Ho YF et al. Nephrotoxic Polypharmacy and risk of contrast Medium-Induced Nephropathy in Hospitalized Patients Undergoing Contrast-Enhanced CT. AJR AM J Roentgenol 2015. PMID: 26397318
5. Hinson JS et al. Risk of Acute Kidney Injury After Intravenous Contrast Media Administration. Ann Emerg Med 2017. PMID: 28131489
6. Kidney Disease Improving Global Outcomes (KDIGO) Guidelines on AKI [Link is HERE]
7. McDonald JS et al. Risk of Intravenous Contrast Material-Mediated Acute Kidney Injury: A Propensity Score-Matched Study stratified by Baseline-Estimated Glomerular Filtration Rate. Radiology 2014. PMID: 24475854
8. McDonald RJ et al. Intravenous Contrast Material Exposure is not an Independent Risk Factor for Dialysis or Mortality. Radiology 2014. PMID: 25203000
9. Nijssen EC et al. Prophylactic Hydration to Protect Renal Function from Intravascular Iodinated Contrast Material in Patients at High Risk of Contrast-Induced Nephropathy (AMACING): A Prospective, Randomised, Phase 3, Controlled, Open-Label, Non-Inferiority Trial. Lancet 2017. PMID: 28233565
10. Reed M et al. The Relative Renal Safety of Iodixanol Compared with Low-Osmolar contrast Media: A Meta-Analysis of Randomized Controlled Trials. JACC Cardiovasc Interv 2009. PMID: 19628188
11. Hinson JS et al Acute Kidney Injury Following Contrast Media Administration in the Septic Patient: A Retrospective Propensity-Matched Analysis. J Crit Care 2019. PMID: 30798098
12. Tirnal RJ et al. Effect of No Prehydration vs Sodium Bicarbonate Prehydration Prior to Contrast-Enhanced Computed Tomography in the Prevention of Postcontrast Acute Kidney Injury in Adults with Chronic Kidney Disease: the Kompas Randomized Clinical Trial. JAMA Intern Med 2020. PMID: 32065601
13. Aycock RD et al. Acute Kidney Injury After Computed Tomography: A Meta-Analysis. Ann Emerg Med 2017. PMID: 28811122
14. Cho A et al. Postcontrast Acute Kidney Injury After Computed Tomography Pulmonary Angiography for acute Pulmonary Embolism. JEM 2019. PMID: 31740158

Post Peer Reviewed By: Mizuho Morrison, DO (Twitter: @mizuhomorrison)