Contrast Induced AKI (CI-AKI)

Madison Bandler, Alexa Serino

KDIGO Criteria for CI-AKI

  • sCr increase by 0.5mg/dl or 25% increase in sCr from baseline 48 hours after radiologic procedure where intravenous contrast was administered

Background

  • Mechanism of injury: Direct toxic effect leading to tubular necrosis and indirect effects on renal blood flow leading to medullary ischemia
  • 2024 KDIGO guidelines updated the term from contrast induced nephropathy to contrast associated nephropathy, as the association exists but AKI can be precipitated by various factors including hypotension, atheroemboli, and medications that can coincide with contrast administration
  • When someone develops an AKI do your due diligence and evaluate for the usual causes of AKI, regardless of when they were given contrast

Who is at risk for CI-AKI?

  • Normal kidney function: incidence of CI-AKI is 1-3%
  • Studies show no increase in contrast associated AKI of patient with GFR > 45 ml/min
  • Pre-existing CKD: Incidence of CA-AKI may be as high as 20% in patients with CKD 4-5 (GFR<30 ml/min)
  • GFR <45 ml/min with comorbidities are at intermediate risk
    • Diabetes o Reduced intravascular volume (CHF, decompensated cirrhosis, dehydration)
    • Taking nephrotoxic medications
    • Older age
  • Arterial contrast carries a higher risk of CA-AKI than venous contrast
  • High volumes of contrast media and repeated contrast administration within a short period are risk factors
  • No real sCr or eGFR threshold below which iodinated contrast is contraindicated, especially in patients for whom imaging will alter management (e.g. acute stroke, PE, STEMI)

Risk reduction strategies

  • IV fluid repletion: KDIGO guidelines give no clear recommendation for rate or duration for optimal protection, but do recommend IV isotonic crystalloid over oral hydration. No differences in major adverse kidney events with normal saline vs. isotonic sodium bicarb
    • American College of Radiology guidelines recommend the use of intravenous isotonic saline at an infusion rate of 100 ml per hour for 6 to 12 hours before and 4 to 12 hours after angiography.
    • The European Society of Cardiology guidelines suggest a rate of 1 to 1.5 ml per kilogram per hour for 12 hours before and up to 24 hours after the procedure
    • Rate and duration can be decreased based on the risk for hypervolemia
      • POSEIDON trial investigated the efficacy of hemodynamic-guided fluid administration to prevent CA-AKI in patients undergoing cardiac catheterization. This randomized, parallel-group, single-blind trial compared a standard fluid administration protocol with a protocol guided by left ventricular end-diastolic pressure (LVEDP)
      • Both groups received 0.9% isotonic saline at 3 mL/kg for 1 hour before the procedure. The control group continued with isotonic saline at 1.5 mL/kg/hr during and for 4 hours after the procedure. The LVEDP-guided group received isotonic saline at rates adjusted based on LVEDP: 5 mL/kg/hr for LVEDP <13 mm Hg, 3 mL/kg/hr for LVEDP 13-18 mm Hg, and 1.5 mL/kg/hr for LVEDP >18 mm Hg.
      • Incidence of CA-AKI was significantly lower in the LVEDP guided group
    • Typically recommend holding diuretics prior to contrast administration, but if patient is volume up, consider administer diuretic and fluid at a rate that matches urine output

Management

  • Medication management: Consider holding nephrotoxic medications such as NSAIDs, RAAS inhibitors, diuretics, zoledronate, methotrexate etc. in people with AKI or eGFR <30 for 24 hours before and 48 hours after contrast administration
  • Pharmacologic intervention: High-dose statins, with or without N-acetylcysteine (NAC), have shown potential benefits in reducing the incidence of contrast-induced AKI
  • Use low-osmolality or iso-osmolality contrast whenever possible and minimize contrast volume
  • Never delay a necessary procedure or image out of concern for worsening renal function

Iodinated contrast in CKD-5/ESRD patients

  • While hemodialysis can remove contrast media, it is not recommended as a prophylactic measure to prevent contrast-induced nephropathy due to the rapid onset of kidney damage post-contrast administration
  • Avoid giving if you are trying to preserve residual kidney function in ESRD particularly with patients on PD

Gadolinium contrast for MRI

  • The risk of nephrogenic systemic fibrosis (NSF) has been significantly reduced with the use of newer gadolinium based contrast agents (GBCAs) that have a higher binding affinity for free gadolinium, such as group II and III agents.
  • Contemporary studies have not reported any new cases of NSF with the use of these agents, though there remains concern about gadolinium deposition in the brain and a possible systemic syndrome attributed to GBCAs, which warrants consideration of alternative imaging modalities when feasible
  • Contemporary studies have not reported any new cases of NSF with the use of these agents, though there remains concern about gadolinium deposition in the brain and a possible systemic syndrome attributed to GBCAs, which warrants consideration of alternative imaging modalities when feasible
  • If a patient with eGFR <30 mL/min per 1.73m2 requires contrasted MRI discuss with Nephrology
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