Acute Kidney Injury - ACH Pediatric Residents
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Transcript Acute Kidney Injury - ACH Pediatric Residents
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
by a rapid decline in GFR”
Previously known as Acute Renal Failure
Now failure represents one end of the spectrum
Classification - pRIFLE
U/O
Risk
eCCl dec 25%
Injury
eCCl dec 50%
Failure
eCCl dec 75%/ <0.3cc/kg/h x 24h/
< 35ml/min/1.73m2 Anuric x 12h
Loss
End-stage
<0.5cc/kg/h x 8h
U/O
<0.5cc/kg/h x 16h
Persistent failure >4wks
Failure > 3 months
Leads to:
Impaired excretion of nitrogenous waste
Impaired water and electrolyte balancing
Impaired acid/base regulation
Impaired vascular tone regulation
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
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
Bleeding
Trauma
Surgery
Vomiting
Diarrhea
Kidney sees less volume:
Sepsis
CHF
Cirrhosis
Vascular - also consider in renal
Diuresis
Diabetes - DM, DI
Drugs
RAS
Thrombus
Takayasu, PAN, KD
Drugs
NSAIDs
ACEi
ARBs
Renal causes
Vascular:
Glomerular:
Microvasculature:
Glomerulonephritis: Acute tubular necrosis
•Post-infectious
-secondary to nephrotoxic
Sickle cell disease
HUS
Tumour lysis
rhabdomyolysis
?Syndromes
Hepatorenal
Cardiorenal
Pulmonary-renal
?Sepsis
inflamm, not all volume
related
•membranoproliferative
•SLE
•HSP
Tubulo/Interstitial:
insults or poor perfusion
Acute interstitial nephritis
-drugs
-infxn
Cortical dysplasia
-hypoxia/ischemia->infarct
-toxins/severe HUS
Hemolytic Uremic
Syndrome
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
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.
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
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…
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
Vascular effect
ACEi, cyclosporine, tacrolimus
Tubular effect
AIN
Proximal: aminoglycosides, amphotericin B,
cisplatin, immunoglobulins, contrast
Distal: NSAIDs, ACEi, lithium, cyclophosphamide
Obstruction: sulfa, acylovir, methotrexate
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…
? 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…
Pre-renal:
Dehydration
Signs of heart failure/cirrhosis/sepsis
Renal:
Edema (nephrotic syndrome)
Purpura (HSP
Post-renal: palpable bladder?
What to order?
BUN, Cr, lytes, fractional excretion of sodium
Urinalysis
On labs…
Everyone gets a urinalysis…
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 (postinfxn)
-hematuria = AIN, vasculitis,
infarction, obstruction
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
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
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…
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
Creatinine is usually elevated
Normal Cr varies by age
Age
Normal range (umol/L)
Newborn
27-88
Infant
18-35
Child
27-62
Adolescent
44-88
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?
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
Ultrasound - in all children if etiology unclear
# of kidneys
Size of kidneys
Obvious parenchymal damage
Obstruction
Thrombus/vessel occlusion
Renal biopsy
Only when diagnosis remains unknown, or
there is a failure to respond to treatment
Approach summary:
pRIFLE met
-estimated CrCl
-oliguria
NORMAL
urinalysis
ABNORMAL
urinalysis
Ultrasound
PRE-RENAL
Low ECF volume
-GI loss
-diuresis
-hemorrhage
RENAL
POST-RENAL
Low vol to kidney
-bilateral ureteric obstruction
-heart failure
-single kidney + ureter obs
-m eds (NSAIDs, ACEi, ARB)
-bladder/urethra obs
-vascular disease
Vascular disorders
Artery
-RAS
-Takayasu, PAN, KD
-can think of drugs here too
Veins
-thrombosis
Parenchymal disorders
Glomerular disorders
Tubular disorders
AIN
-drugs
-infection
-autoimmune
ATN
-ischemia
-contrast
plugged
-crystals
-globins
-drugs
Treatment
Principles:
1. FEN
2. Avoid complications
3. Treat underlying cause
Generally pediatric nephrology will be involved.
FEN - fluids
Child can be hypo-, eu- or hypervolemic.
FLUID STATUS
Hypovolemia
Goal:
maintain renal perfusion
Euvolemia
Hypervolemia
Type Title Here
Crystalloids (NS)
-bolus, rpt
-no change?
Consider invasive monitors
Monitor ins/outs
-daily weights
-ins=outs + insensibles
Fluid removal/restriction
-furosemide (2-5mg/kg)
-no change?
Consider RRT
HTN can occur and is usually secondary to volume overload.
Treatment based on diuretic response, severity.
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 - 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 - electrolytes
Hyperphosphatemia:
Low phosphate diet
Binders
Hypocalcemia:
Calcium gluconate
Can pre-empt if sodium bicarb being given
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
Including making things worse…so no:
Aminoglycosides
NSAIDs
Antifungals
Immunosuppressive drugs
Contrast media
Renal Replacement Therapy
(RRT)
Indications:
1. Uremia s/s - pericarditis, neuropathy,
decline
2. Azotemia - BUN >36
3. Refractory fluid overload - HTN, pulm
edema, CHF
4. Refractory hyperK, hypo/hyperNa, acidosis
5. Nutritional support with fluid balance issues
RRT
Options:
Continuous renal replacement therapy
Peritoneal dialysis
Hemodialysis
Prognosis
Mortality: 60% (critically ill)
20-25% go on to have some degree of
chronic renal issues
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
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-anddiagnosis-of-acute-kidney-injury-acute-renal-failure-inchildren?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-acutekidney-injury-acute-renal-failure-inchildren?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.