Contrast Induced AKI (CI-AKI)

Alana Jones

CK-AKI Definition (KDIGO Criteria): 

  • 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 
  • Precipitating factors: hypotension, atheroemboli, and medications

Who is at risk for CI-AKI? 

  • 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 -> intermediate risk 
  • 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 
  • Risk factors: diabetes, reduced intravascular volume (CHF, decompensated cirrhosis, dehydration), concurrent nephrotoxic meds, old age 
  • Arterial contrast carries a higher risk of CA-AKI than venous contrast 
  • High volumes of contrast media (e.g. with repeated administration within a short period) 

NOTE: No actual 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 
  • POSEIDON trial: In CKD, LVEDP-guided hydration > standard hydration for preventing CI-AKI (1.5 mL/kg/hr) 
  • Pre-procedure: normal saline (NS) at 3 ml/kg for 1 hour 
  • Post-procedure: sliding-scale based on LVEDP (for 4 hrs) 
  • 13 mmHg -> 5mL/kg/hr 
  • 13-18 mmHg -> 3mL/kg/hr 
  • 18 mm Hg -> 1.5mL/kg/hr 
  • KDIGO guidelines: IV isotonic crystalloid > oral hydration. No differences in major adverse kidney events with normal saline vs. isotonic sodium bicarb 
  • American College of Radiology: recommend the use of intravenous isotonic saline at 100ml/hour for 6 to 12 hours before and 4 to 12 hours after angiography. 
  • European Society of Cardiology: 1 to 1.5 ml/kg/hr for 12 hours before and up to 24 hours after angiography 
  • Rate and duration can be decreased based on the risk for hypervolemia

Diuretic management 

  • If euvolemic -> Consider holding diuretics prior to 
  • If hypervolemic -> consider diuretic and fluid at a rate that matches UOP 
  • 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

Iodinated Contrast in CKD-5/ESRD 

  • While HD can remove contrast, it is NOT recommended as a prophylactic measure to prevent CIN due to the rapid onset of kidney damage post-contrast administration 
  • Avoid if trying to preserve residual kidney function, particularly in those on PD

Gadolinium contrast for MRI 

  • For patients with eGFR <30 mL/min per 1.73m2, nephrology consult is REQUIRED 
  • 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
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