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ACUTE RENAL FAILURE. Academic Half Day February 9, 2012. Objectives. To review: the etiologies of acute kidney injury (AKI) in the pediatric population the work-up/diagnosis of AKI the management of AKI What is AKIs? “abrupt reduction in kidney function as measured

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acute renal failure

ACUTE RENAL FAILURE

Academic Half Day

February 9, 2012

objectives
Objectives

To review:

  • the etiologies of acute kidney injury (AKI) in the pediatric population
  • the work-up/diagnosis of AKI
  • the management of AKI
  • What is AKIs?

“abrupt reduction in kidney function as measured

by a rapid decline in GFR”

  • Previously known as Acute Renal Failure
  • Now failure represents one end of the spectrum
  • Etiology is variable
  • Definitions/classifications have varied in the literature…
classification prifle
Classification - pRIFLE

U/O

<0.5cc/kg/h x 8h

Risk

Injury

Failure

Loss

End-stage

eCCl dec 25%

eCCl dec 50%

U/O

<0.5cc/kg/h x 16h

eCCl dec 75%/

< 35ml/min/1.73m2

<0.3cc/kg/h x 24h/

Anuric x 12h

Persistent failure >4wks

Failure > 3 months

slide4
Leads to:
  • Impaired excretion of nitrogenous waste
  • Impaired water and electrolyte balancing
  • Impaired acid/base regulation
  • Impaired vascular tone regulation
burden of disease
Burden of disease

Incidence (US): 0.8/100 000; ~1/10 in ICU

  • Increasing

Independent risk factor for ICU mortality

Increases length of hospital stay

May lead to chronic renal failure (40-50% ICU)

etiologies a general approach
Etiologies: a general approach

Though likely multifactorial, can be divided into:

Pre-renal

Renal

Post-renal

pre renal causes any cause which results from kidney seeing to little blood flow
Volume deplete:

GI

Vomiting

Diarrhea

Bleeding

Trauma

Surgery

Diuresis

Diabetes - DM, DI

Drugs

Kidney sees less volume:

Sepsis

CHF

Cirrhosis

Vascular - also consider in renal

RAS

Thrombus

Takayasu, PAN, KD

Drugs

NSAIDs

ACEi

ARBs

Pre-renal causes:Any cause which results from kidney seeing to little blood flow
renal causes
Renal causes

Vascular:

Microvasculature:

  • Sickle cell disease
  • HUS
  • Tumour lysis
  • rhabdomyolysis

?Syndromes

  • Hepatorenal
  • Cardiorenal
  • Pulmonary-renal
  • Glomerular:
  • Glomerulonephritis:
  • Post-infectious
  • membranoproliferative
  • SLE
  • HSP

Tubulo/Interstitial:Acute tubular necrosis -secondary to nephrotoxic insults or poor perfusion

Acute interstitial nephritis -drugs -infxn

Cortical dysplasia -hypoxia/ischemia->infarct -toxins/severe HUS

?Sepsis inflamm, not all volume related

hemolytic uremic syndrome
Hemolytic UremicSyndrome

History of Ecoli, Shigella, shiga-toxin…

Atypical (non-diarrhea, non-shiga-toxin)

Hemolytic anemia with fragmented RBCs

Thrombocytopenia

Renal injury

CNS, liver, pancreas can also be affected

post infectious glomerulonephritis
Post-infectious glomerulonephritis

Occurs in ages 5-12, post-GAS.

Presentation can be asymptomatic to nephritis complete with gross hematuria, proteinuria, HTN, edema

Labs: abnormal urinalysis, low complement

Rx: supportive.

Prognosis: most make complete recovery.

slide11
HSP

-Causes renal issues d/t IgA deposition.

-A/W palpable purpura, arthritis, abdo pain.

-Renal more likely to be an issue in older kids

-Rx: if crescenteric, GN - steroids.

-prognosis: often relapses. Can have late deterioration even if full recovery. 10-30% adults go on to have end-stage disease.

acute tubular necrosis
Acute TubularNecrosis

Describes an end effect of tubular damage…

  • Secondary to perfusion insults
  • Secondary to toxins

Change in blood flow, obstruction and passive filtrate backflow into tubular cells can cause a cycle leading to further death…

slide13
AIN

Drugs (71%) - 1/3 antibiotics

  • Penicillins, cephalosporins, NSAIDs, sulfonamides, cipro, rifampin, PPIs, allopurinol… and more

Infection (15%)

  • Strep, Legionella, leptospirosis, CMV, EBV… many

Tubulointersitial nephritis and uveitis (5%)

Autoimmune: SLE, Sjogren’s

Sarcoidosis

Idiopathic (8%)

nephrotoxins
Nephrotoxins

Vascular effect

  • ACEi, cyclosporine, tacrolimus

Tubular effect

  • Proximal: aminoglycosides, amphotericin B, cisplatin, immunoglobulins, contrast
  • Distal: NSAIDs, ACEi, lithium, cyclophosphamide
  • Obstruction: sulfa, acylovir, methotrexate

AIN

post renal causes
Post-renal causes

Two kidneys - distal or bilateral proximal obstruction

Single kidney - obstruction anywhere

  • Posterior urethral valves
  • Ureteropelvic junction obstruction
  • Ureterovesicular junction obstruction
  • Ureterocele
  • Stones
  • Tumour
  • Hemorrhagic cystitis
  • Neurogenic bladder
on history
On history…

? pre-renal:

  • Vomiting, diarrhea, bleeding, sepsis, dec PO
  • Drug use - inc NSAIDs

? renal:

  • Bloody diarrhea? (HUS) Recent illness? (PSGN) Crush injury?
  • Drug use: aminoglycosides, antifungals, chemo
  • Associated lung/heart/liver symptoms? (dual organ)

? post-renal:

on physical
On physical…

Pre-renal:

  • Dehydration
  • Signs of heart failure/cirrhosis/sepsis

Renal:

  • Edema (nephrotic syndrome)
  • Purpura (HSP

Post-renal: palpable bladder?

what to order
What to order?

BUN, Cr, lytes, fractional excretion of sodium

Urinalysis

on labs
NORMAL:

-pre-renal (may be concentrated)

-post-renal

-ATN

ABNORMAL:

-brown granular/epithelial

casts = ATN

-red cell casts =

glomerulonephritis

-proteinuria = glomerular

-pyuria, white cell casts = UTI

or glomerulonephritis (post-

infxn)

-hematuria = AIN, vasculitis,

infarction, obstruction

On labs…

Everyone gets a urinalysis…

and even more information from urine
And even more information from urine…

Urine osmolality:

  • Typically low in ATN (<350 mosmol/kg)
  • Typically high in pre-renal disease (>500)

Urine volume:

Often low, especially given criteria for AKI.

However, some ATN is non-oliguric

Urine eosinophils

Urine sodium…

sodium excretion
Sodium excretion

Why? Helps distinguish pre-renal vs ATN…

  • >30-40 mEq/L = ATN
  • <10 mEq/L = effective volume depletion(20-30 in infants)
  • BUT what if there is a large urine output?
fractional excretion of sodium
Fractional Excretion of Sodium

FENa compensates for the urine output…

UNa x PCr

PNa x UCr

…can also be thought of as

UNa/PNa

UCr/PCr

<1% --> pre-renal disease

1-2% --> ??

>2% --> ATN

bloodwork
Bloodwork…

CBC: look for MAHA, thrombocytopenia

Extended lytes. Renal injury can result in:

  • Hyperkalemia
  • Hyperphosphatemia
  • Hypocalcemia
  • Metabolic acidosis

Other options, depending on history: ANCA,

ANA, ASOT, complement, drug levels…

and of course creatinine
And of course, creatinine

Creatinine is usually elevated

  • Normal Cr varies by age
  • Note Cr can NOT be used to estimate GFR in acute kidney injury…
  • This is why the search is on for a “troponin of the kidneys”
troponin of the kidneys
Troponin of the kidneys?

Unfortunately, not yet… Some ideas:

  • Urinary neutrophil gelatinase-associated lipocalin (NGAL)
      • Increased 50-fold, and 24h before serum Cr
      • Has been shown to predict AKI severity in SLE, HUS, renal transplant patients
  • Kidney injury molecule - 1 (KIM-1)
  • IL-18
imaging
Imaging

Ultrasound - in all children if etiology unclear

  • # of kidneys
  • Size of kidneys
  • Obvious parenchymal damage
  • Obstruction
  • Thrombus/vessel occlusion
renal biopsy
Renal biopsy

Only when diagnosis remains unknown, or

there is a failure to respond to treatment

treatment
Treatment

Principles:

  • FEN
  • Avoid complications
  • Treat underlying cause

Generally pediatric nephrology will be involved.

fen fluids
Child can be hypo-, eu- or hypervolemic. FEN - fluids

HTN can occur and is usually secondary to volume overload.

Treatment based on diuretic response, severity.

fen electrolytes
FEN - electrolytes

Hyperkalemia - if severe (>7) - C BIG K Die…

  • Don’t give K (IVs, low K diet)
  • stabilize the cardiac membrane - IV calcium gluconate
  • Move K ECF -> ICF by:
      • Insulin (with glucose)
      • Sodium bicarb
      • Beta agonists
  • Remove K from the body - kayexalate
  • Can try diuretics - unlikely to do enough
  • RRT if the above doesn’t work
fen electrolytes1
FEN - electrolytes

Acidosis

  • Respiratory compensation can be enough
  • Sodium bicarb ONLY if life-threatening and/or contributing to hyperkalemia
      • Def not if pH >7.2 or bicarb >14mEq/L
      • Can decrease Ca further -> seizures
      • Can increase intravascular volume
  • If refractory volume overload, hypernatremia -> RRT
fen electrolytes2
FEN - electrolytes

Hyperphosphatemia:

  • Low phosphate diet
  • Binders

Hypocalcemia:

  • Calcium gluconate
  • Can pre-empt if sodium bicarb being given
fen nutrition
FEN - Nutrition

AKI is a catabolic state

Ensure adequate calories

- 120kcal/kg/d in infants

- usual maintenance for children

PO -> enteral -> TPN

If fluid balance off with adequate nutrition: RRT

avoid complications
Avoid complications

Including making things worse…so no:

Aminoglycosides

NSAIDs

Antifungals

Immunosuppressive drugs

Contrast media

renal replacement therapy rrt
Renal Replacement Therapy (RRT)

Indications:

  • Uremia s/s - pericarditis, neuropathy, decline
  • Azotemia - BUN >36
  • Refractory fluid overload - HTN, pulm edema, CHF
  • Refractory hyperK, hypo/hyperNa, acidosis
  • Nutritional support with fluid balance issues
slide37
RRT

Options:

Continuous renal replacement therapy

Peritoneal dialysis

Hemodialysis

prognosis
Prognosis

Mortality: 60% (critically ill)

20-25% go on to have some degree of chronic renal issues

take home points
Take home points

Etiology:

Best divided into pre-, renal and post-renal

Work-up:

Urinalysis, ultrasound, bloodwork…

Treatment:

Fluids - close balance

Electrolytes - esp K, PO4, Ca

Acidosis

Nutrition

Dialysis - talk later today

references
References

Akcan-Arikan A, Zappitelli M, Loftis L, Washburn K, Jerrerson L, and Goldstein S. Modified RIFLE criteria in critically ill children with acute kidney injury. Kidney International; 2007: 71: 1028-35.

Basu R, Devarajan P, Wong H, and Wheeler S. An update and review of acute kidney injury in pediatrics. Pediatric Critical Care Medicine; 2011: 12(3): 339-47.

Imam A. Clinical presentation, evaluation, and diagnosis of acute kidney injury (acute renal failure) in children. Uptodate. Accessed Feb 8, 2012 at http://www.uptodate.com.ezproxy.lib.ucalgary.ca/contents/clinical-presentation-evaluation-and-diagnosis-of-acute-kidney-injury-acute-renal-failure-in-children?source=search_result&search=acute+kidney+injury&selectedTitle=2~150

Imam A. Prevention and management of acute kidney injury (acute renal failure) in children. Uptodate. Accessed Feb 8, 2012 at http://www.uptodate.com.ezproxy.lib.ucalgary.ca/contents/prevention-and-management-of-acute-kidney-injury-acute-renal-failure-in-children?source=search_result&search=acute+kidney+injury&selectedTitle=1~150

Kliegman R, Stanton B, Geme J, Schor N, and Behrman R. Nelson Textbook of Pediatrics 19th e. Elsevier; 2011: 1814-22.