Prevention and treatment of acute kidney injury in the ICU

Farmer Prevention and Treatment of Acute Kidney Injury in the ICU... Prevention and Treatment of Acute Kidney Injury in the ICU J... Arterial Vasodilatation and Renal Vasoconstriction in

Dr Farmer

Prevention and Treatment of Acute Kidney Injury in the ICU

Prevention and Treatment of Acute Kidney

Injury in the ICU

J Christopher Farmer

Epidemiology and Pathophysiology

Increasing Incidence of AKI

Nash, et al: Am J Kidney Dis; 2002, 39:390

Arterial Vasodilatation and Renal

Vasoconstriction in Patients with Sepsis

Diagnosis and Classification of AKI

Diagnostic Criteria for AKI

An abrupt (within 48 hours) reduction in

kidney function currently defined as:

1.An absolute increase in serum creatinine of more than

or equal to 0.3 mg/dl, or

2.A percentage increase in serum creatinine of more

than or equal to 50% (1.5 fold from baseline), or

3.A reduction in urine output (documented oliguria of

less than 0.5 ml/kg per hour for more than 6 hours)

Mehta et al: Critical Care; 2007, 11:R31-R39

“RIFLE” Criteria for AKI

Bellomo & the ADQI workgroup: Critical Care; 2004, 8:R204-R212

Classification of AKI Severity

Mehta et al: Critical Care; 2007, 11:R31-R39

Mortality Associated with Rising Serum Creatinine

Unadjusted Adjusted for age & sex Multivariable analyses

Chertow, et al: J Am Soc Nephrol; 2005, 16:3365-3370

FENa = (UNa/PNa) / (UCr/PCr) X 100

 Calculating the FENa is useful in AKI only in the presence of oliguria

 In patients with prerenal azotemia, the FENa is usually less than 1%

 In ATN, the FENa is greater than 1%

 Exceptions to this rule are ATN caused by radiocontrast nephropathy, severe burns, acute glomerulonephritis, and rhabdomyolysis

 In the presence of liver disease, FENa can be less than 1% in the

presence of ATN

 Because administration of diuretics may cause the FENa to be greater than 1%, these findings cannot be used as the sole indicators in AKI

FEUrea = (Uurea/Purea) / (UCr/PCr) X 100

 Fractional excretion of urea (FEUrea) can be

obtained since urea transport is not affected by

diuretics

 FEUrea of less than 35% is suggestive of a prerenal state

Early Detection of AKI is Difficult

Jo, et al: Clin J Am Soc Nephrol; 2007, 2:356-365

“Earlier” Detection of AKI

Induction of NGAL protein after unilateral or bilateral ischemia

Mishra, et al: J Am Soc Nephrol; 2003, 14:2534-2543

Urinary IL-18 as an Early Marker of AKI

IL-18 as a marker for the diagnosis of ATN and delayed graft function:

•ROC - discriminatory power

of IL-18 for the diagnosis of ATN

•The area under the ROC curve was 0.95

Parikh et al: AJKD; 2004, 43:405-14

Future “Cardiac Biomarkers” of AKI?

Parikh et al: KI; 2006, 70:199 -203

Biomarker Sample Source Assay Commercial Development

NGAL plasma Western blot In development (Biosite) NGAL urine Western blot In development (Abbott)

Cystatin-C plasma Immunonephelometry In development (Dade-

Behring)

Coming soon?

Prevention of AKI

Maintaining Renal Perfusion Pressure

 No absolute number is considered adequate with regard to mean

arterial pressure, and target mean arterial pressure should be

individualized based on the patient's baseline physiology

 Vasopressors should be used to improve perfusion pressure only after adequate volume repletion is accomplished

 No reliable evidence that norepinephrine is associated with increased risk of AKI when used to treat arterial hypotension

 Intra-abdominal hypertension is associated decreased renal perfusion and may result in AKI

 Prompt recognition, monitoring, and early surgical treatment offer the best potential for recovery

Role of Loop Diuretics in AKI

 maintaining a greater urine flow to flush out the tubules with loop

diuretics has been advocated to prevent AKI

 Two meta-analyses have pooled studies evaluating the role of loop diuretics in the prevention of AKI

– The first systematic review compared fluids alone with diuretics in people

at risk for AKI from various causes and found no benefit from diuretics with regard to its incidence, need for dialysis, or mortality

– In the second recent meta-analysis (RCTs, n = 849 patients), no difference among patients treated with loop diuretics was found in hospital mortality, need for renal replacement therapy, or number of dialysis sessions needed

Treatment of AKI

John et al: Chest 2007;132:1379-1388

Principles of Solute Transport in Hemodialysis and Hemofiltration

Hemofiltration versus Hemodiafiltration

Definitions of RRT Modalities

Pannu et al: JAMA; 2008, 299: 793-805

Renal Replacement Therapy in Patients with Acute Renal Failure

Pannu et al: JAMA; 2008, 299: 793-805

Standard IHD versus Slow Low Efficiency Dialysis (SLED)

Initiation of RRT

John, S et al Chest 2007;132:1379-1388

Potential Complications with CRRT

AKI

– Prognosis and mortality

– Maintain renal perfusion status, treat sepsis

promptly, avoid nephrotoxins

renal replacement therapies