Acute Kidney Injury

1
Acute Kidney Injury

• Do we know what we mean?

2
Definition of AKI

• There are more than 35 definitions of AKI
  (formerly acute renal failure) in literature!
• Mehta R, Chertow G Acute renal failure
  definitions and classification Time for change?
  Journal of American Society of Nephrology 2003
  142178-2187.

3
Definition of AKI

• RIFLE classification
• AKIN classification

4
RIFLE classification

• Bellomo R, Ronco C, Kellum J, et al. Acute
  renal failure-definition, outcome measures,
  animal models, fluid therapy and information
  technology needs The Second International
  Consensus Conference of the Acute Dialysis
  Initiative (ADQI) Group. Critical Care 2004
  8R204-R212.

5
AKIN classification

• Modification of the RIFLE classification by Acute
  Kidney Injury Network (AKIN).
• Recognizes that small changes in serum creatinine
  (gt0.3 mg/dl) adversely impact clinical outcome.
• Uses serum creatinine, urinary output and time.
• Coca S, Peixoto A, Garg A, et al. The
  prognostic importance of a small acute decrement
  in kidney function in hospitalized patients a
  systematic review and meta-analysis. American
  Journal of Kidney Diseases 2007 50712-720.

6
AKIN classification
AKIN stage Serum Creatinine Criteria Urinary Output Criteria Time
1 ? Cr 0.3 mg/dL or ? 150-200 from baseline lt 0.5 mL/kg/hr gt 6 hrs
2 ? Cr to gt 200-300 from baseline lt 0.5 mL/kg/hr gt 12 hrs
3 Cr to gt 300 from baseline or Cr 4mg/dL with an acute rise of at least 0.5 mg/dL lt 0.5 mL/kg/hr or anuria X 24 hrs X 12 hrs
Patients needing RRT are classified stage 3
despite the stage they were before starting
RRT Mehta R, Kellum J, Shah S, et al. Acute
kidney Injury Network Report of an Initiative to
improve outcomes in Acute Kidney
Injury. Critical Care 2007 11 R31.
7
Definition of AKI

• AKI is an abrupt (within 48 hrs) reduction in
  kidney function currently defined as an absolute
  increase in serum creatinine of 0.3 mg/dL (
  26.4 µmol/L), a percentage increase in serum
  creatinine of 50, or a reduction in urine
  output (documented oliguria of lt 0.5 mL/kg/hr for
  gt 6hrs.
• Mehta R, Kellum J, Shah S, et al. Acute kidney
  Injury Network Report of an Initiative to
  improve outcomes in Acute Kidney Injury.
  Critical Care 2007 11 R31.

8
Epidemiology

• AKI occurs in
• 7 of hospitalized patients.
• 36 67 of critically ill patients (depending on
  the definition).
• 5-6 of ICU patients with AKI require RRT.
• Nash K, Hafeez A, Hou S Hospital-acquired renal
  insufficiency. American Journal of Kidney
  Diseases 2002 39930-936.
• Hoste E, Clermont G, Kersten A, et al. RIFLE
  criteria for acute kidney injury are associated
  with hospital mortality in critically ill
  patients A cohort analysis. Critical Care 2006
  10R73.
• Osterman M, Chang R Acute Kidney Injury in the
  Intensive Care Unit according to RIFLE. Critical
  Care Medicine 2007 351837-1843.

9
Mortality according to RIFLE

• Mortality increases proportionately with
  increasing severity of AKI (using RIFLE).
• AKI requiring RRT is an independent risk factor
  for in-hospital mortality.
• Mortality in pts with AKI requiring RRT 50-70.
• Even small changes in serum creatinine are
  associated with increased mortality.
• Hoste E, Clermont G, Kersten A, et al. RIFLE
  criteria for acute kidney injury are associated
  with hospital mortality in critically ill
  patients A cohort analysis. Critical Care 2006
  10R73.
• Chertow G, Levy E, Hammermeister K, et al.
  Independent association between acute renal
  failure and mortality following cardiac surgery.
  American Journal of Medicine 1998 104343-348.
• Uchino S, Kellum J, Bellomo R, et al. Acute
  renal failure in critically ill patients A
  multinational, multicenter study. JAMA 2005
  294813-818.
• Coca S, Peixoto A, Garg A, et al. The
  prognostic importance of a small acute decrement
  in kidney function in hospitalized patients a
  systematic review and meta-analysis. American
  Journal of Kidney Diseases 2007 50712-720.

10
Diagnosis

• Serum Creatinine
• Urine Output
• Time

11
Limitations of SCr
Dennen P, Douglas I, Anderson R, Acute Kidney
Injury in the Intensive Care Unit An update and
primer for the Intensivist. Critical Care
Medicine 2010 38261-275.
12
Common causes of AKI in ICU

• Sepsis
• Major surgery
• Low cardiac output
• Hypovolemia
• Medications (20)
• Uchino S, Kellum J, Bellomo R, et al. Acute
  renal failure in critically ill patients A
  multinational, multicenter study. JAMA 2005
  294813-818.

13
Common causes of AKI in ICU

• Hepatorenal syndrome
• Trauma
• Cardiopulmonary bypass
• Abdominal compartment syndrome
• Rhabdomyolysis
• Obstruction
• Dennen P, Douglas I, Anderson R, Acute Kidney
  Injury in the Intensive Care Unit An update and
  primer for the Intensivist. Critical Care
  Medicine 2010 38261-275.

14
Nephrotoxins

• NSAIDs
• Aminoglycosides
• Amphotericin
• Penicillins
• Acyclovir
• Cytotoxics
• Radiocontrast dye
• Dennen P, Douglas I, Anderson R, Acute Kidney
  Injury in the Intensive Care Unit An update and
  primer for the Intensivist. Critical Care
  Medicine 2010 38261-275.

15
Prevention of AKI in ICU

• Recognition of underlying risk factors
• Diabetes
• CKD
• Age
• HTN
• Cardiac/liver dysfunction
• Maintenance of renal perfusion
• Avoidance of hyperglycemia
• Avoidance of nephrotoxins
• Dennen P, Douglas I, Anderson R, Acute Kidney
  Injury in the Intensive Care Unit An update and
  primer for the Intensivist. Critical Care
  Medicine 2010 38261-275.

16
Prevention of Contrast-Induced Nephropathy

• Avoid use of intravenous contrast in high risk
  patients if at all possible.
• Use pre-procedure volume expansion using isotonic
  saline (?bicarbonate).
• NAC
• Avoid concomitant use of nephrotoxic medications
  if possible.
• Use low volume low- or iso-osmolar contrast
• Dennen P, Douglas I, Anderson R, Acute Kidney
  Injury in the Intensive Care Unit An update and
  primer for the Intensivist. Critical Care
  Medicine 2010 38261-275.

17
Prevention of AKI in hepatic dysfunction

• Intravenous albumin significantly reduces the
  incidence of AKI and mortality in patients with
  cirrhosis and SBP.
• Albumin decreases the incidence of AKI after
  large volume paracentesis.
• Albumin and terlipressin decrease mortality in
  HRS.
• Sort P, Navasa M, Arroyo V, et al. Effect of
  intravenous albumin on renal impairment and
  mortality in patients with cirrhosis and
  spontaneous bacterial peritonitis. New England
  Journal of Medicine 1999 341403-409.
• Gines P, Tito L, Arroyo V, et al. Randomised
  comparative study of therapeutic paracentesis
  with and without intravenous albumin in
  cirrhosis. Gastroenterology 1988 941493-1502.
• Gluud L, Kjaer M, Christensen E Terlipressin
  for hepatorenal syndrome. Cochrane Database
  Systematic Reviews 2006 CD005162.

18
Management of AKI in ICU

• Maintain renal perfusion
• Correct metabolic derangements
• Provide adequate nutrition
• ? Role of diuretics

19
Maintaining renal perfusion

• Human kidney has a compromised ability to
  autoregulate in AKI.
• Maintaining haemodynamic stability and avoiding
  volume depletion are a priority in AKI.
• Kelleher S, Robinette J, Conger J Sympathetic
  nervous system in the loss of autoregulation in
  acute renal failure. American Journal of
  Physiology 1984 246 F379-386.

20
Maintaining renal perfusion

• Current studies do not include patients with
  established AKI.
• The individual BP target depends on age,
  co-morbidities (HTN) and the current acute
  illness.
• A generally accepted target remains MAP 65.
• Bourgoin A, Leone M, Delmas A, et al.
  Increasing mean arterial pressure in patients
  with septic shock Effects on oxygen variables
  and renal function. Critical Care Medicine 2005
  33780-786.

21
Volume resuscitation which fluid?

• SAFE study no statistical difference between
  volume resuscitation with saline or albumin in
  survival rates or need for RRT.
• Post hoc analysis albumin was associated with
  increased mortality in traumatic brain injury
  subgroup and improved survival in septic shock
  patients.
• Finfer S, Bellomo R, Boyce N, et al. A
  comparison of albumin and saline for fluid
  resuscitation in the intensive care unit. New
  England Journal of Medicine 2004 350 2247-2256.

22
Volume resuscitation how much fluid?

• Fluid conservative therapy decreased ventilator
  days and didnt increase the need for RRT in ARDS
  patients.
• Association between positive fluid balance and
  increased mortality in AKI patients.
• Wiedeman H, Wheeler A, Bernard G, et al.
  Comparison of two fluid management strategies in
  acute lung injury. New England Journal of
  Medicine 2006 3542564-2575.
• Payen D, de Pont A, Sakr Y, et al. A positive
  fluid balance is associated with worse outcome in
  patients with acute renal failure. Critical Care
  2008 12 R74.

23
Which inotrope/vasopressor?

• There is no evidence that from a renal protection
  standpoint, there is a vasopressor agent of
  choice to improve kidney outcome.
• Dennen P, Douglas I, Anderson R, Acute Kidney
  Injury in the Intensive Care Unit An update and
  primer for the Intensivist. Critical Care
  Medicine 2010 38261-275.

24
Renal vasodilators?

• Renal dose dopamine doesnt reduce the
  incidence of AKI, the need for RRT or improve
  outcomes in AKI.
• It may worsen renal perfusion in critically ill
  adults with AKI.
• Side effects of dopamine include increased
  myocardial oxygen demand, increased incidence of
  atrial fibrillation and negative
  immuno-modulating effects.
• Lauschke A, Teichgraber U, Frei U, et al.
  Low-dose dopamine worsens renal perfusion in
  patients with acute renal failure. Kidney 2006
  691669-1674.
• Argalious M, Motta P, Khandwala F, et al.
  Renal dose dopamine is associated with the risk
  of new onset atrial fibrillation after cardiac
  surgery. Critical Care Medicine 2005
  331327-1332.

25
Avoid hyperglycemia
26
Correction of acidosis?
27
Any role for diuretics?
28
Avoid nephrotoxins
29
Nutrition
30
Renal replacement therapy
31
Timing of RRT
32
Dosing of RRT
33
Modality of RRT