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Preventing Nephropathy Induced by Contrast Medium Brendan J

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Preventing Nephropathy Induced by Contrast Medium Brendan J Powered By Docstoc
					    Preventing Nephropathy
  Induced by Contrast Medium

Brendan J. Barrett, M.B., and Patrick S. Parfrey, M.D.

       N Engl J Med 2006; 354:379-386, Jan 26, 2006.
                     Clinical Practice
                  指導教師:吳明儒主任
                   PGY學員:葉政男
   A 71-year-old man with type 2 diabetes and
    hypertension is referred for coronary
    angiography. His medications include
    metformin and a thiazide. Before the
    angiogram, his serum creatinine level is 1.8
    mg per deciliter (160 µmol per liter),
    yielding an estimated GFR of 40 ml per
    minute per 1.73 m2 of body-surface area.
    What can be done to reduce the risk that an
    angiographic contrast medium will worsen
    his kidney function?
              The Clinical Problem
1.Contrast-induced nephropathy(CIN): Clinically
  important injury is much less common
Contrast nephrotoxicity was first described on 1960S
The third most common cause of hospital-acquired
renal failure and accounts for approximately11%
of cases
2.Definition:fixed (0.5 mg/dl [44 µmol per liter]) or
  proportionate (25 percent) rise in serum creatinine
  levels after exposure to the contrast medium
3.Associated with baseline renal function
                  Risk Factors

1.DM ,age over 75 years, periprocedural volume
depletion, heart failure, cirrhosis or nephrosis, hypertension,
proteinuria, concomitant use of NSAID, and intraarterial
injection .
2. AMI or PCI, hypotension or use of an aortic balloon
   pump(IABP)a higher rate of acute renal failure after
   exposure to a contrast medium
3. Dose of contrast medium V.S Kidney function
                   Prognosis
1.CIN:ususally transient, serum creatinine peaking at 3
   days and returning to baseline within 10 days after
   administration of contrast
2. Appreciable nephropathy is unlikely to develop if
   the serum creatinine level does not increase by more
   than 0.5 mg per deciliter within 24 hours
3.Outcome VS. Declined renal function & Patient’s
   condition
                 Pathogenesis
Three core elements are intertwined in the
pathophysiology of CIN:
(1)Direct toxicity of iodinated contrast to nephrons,
(2)Microshowers of atheroemboli to the kidneys
(3) Contrast- and atheroemboli-induced intrarenal
vasoconstriction
But the pathogenesis is unclear in human
Pathophysiology of contrast-induced nephropathy involves acute ischemia to the outer
medulla—the most vulnerable part of the kidney—as a result of direct cellular toxicity
and sustained intrarenal vasoconstriction and reduction in renal blood flow. This
process is worsened by multiple factors, including hypoxia, anemia, and systemic
hypoperfusion. N Engl J Med 1995;332(10):647–55
         Strategies and Evidence
   Evaluation of Risk:
1.Not necessary to measure the serum creatinine levels
of every patient
2.Measurements should be made before intraarterial use of
the medium and in patients with a history of kidney disease,
proteinuria, kidney surgery, diabetes, hypertension, or gout
3. Hold Metformin until greater than 40 ml per minute
per 1.73 m2 and for the 48 hours before exposure
of the patient to the contrast medium.
   J Am Coll Cardiol 2004;44(7):1393–9
Prevention
 Renal protection for patients who undergo
            contrast procedures
End-organ protection for at-risk patients who have CKD:
(1)long-term cardiorenal protection
blood pressure control in CKD to a target of
  approximately 125/75 mm Hg
ACEI(esp. Type I DM) and ARB( esp. type 2 DM)
(2) removal of renal toxins
(3) prevention measures performed before contrast
     exposure
                    Guidelines
1.Assessment of risk factors
2.Consideration of alternative imaging techniques,
discontinuation of nephrotoxic drugs, and use of low-
osmolar or iso-osmolar contrast mediums in limited doses
3.Maintaining adequate hydration and the administration of
  additional fluids
4.Multiple infusions of contrast medium within a short
 period of time and the use of mannitol or diuretics are to be
avoided
5. N-acetylcysteine or other potential prophylactic drug
therapies without specially reconmending in America
    Summary and Recommendations
1.Normal renal fuction and no other risk factorsGO﹗
2.Reduced renal functionMeasure the serum Cr level
estimated GFR.If GFR< 50 ml/minute/1.73 m2,
&combination with other risk factors Consider alternative
imaging approaches
3.Low-osmolar agent with the minimal dose necessary, and
Check serum Cr should be repeated 24 to 48 hr after the
contrast medium
4.Hold NSAID and Diuretics 12hr before and after contrast
  Holf Metformin 48hr before contrast
5.N/S 1ml/kg/hr 12hr before and after contrast IV
結 束

				
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