8. Kidney function is dependent on
Adequacy of blood supply to the kidney
– Prerenal
Integrity of renal parenchyma
– Renal
Patency of urinary tract
– Post renal
9. Formerly referred to as acute renal failure (ARF).
Defined as an “sudden deterioration in kidney function results
in the inability to maintain fluid and electrolyte homeostasis”
Acute Kidney Injury (AKI): Definition
10. Impairment of
nitrogenous waste
product excretion
Loss of water regulation
Loss of electrolytes
regulation
Loss of acid-base [H+]
regulation
Acute Kidney Injury
Disturbance of renal
physiological functions
11. Diagnosis of AKI is Often Delayed
• Serum creatinine alone is a poor indicator of renal function
• Serum creatinine varies widely with age, gender, diet, muscle
mass, medications, and hydration status
• Up to 50% of kidney function may be lost before serum
creatinine even begins to rise
Each doubling of creatinine
kidney function cuts in half
13. Normal GFR Values for Children
Estimated Creatinine Clearance (ml/min/1.73 m2)
“Schwartz Formula”
eCCL = k × Height / SCR
K is 0.33 in pre-term and 0.45 for term infants <1 year
K is 0.55 in children and adolescent girls, and 0.7 in adolescent boys
14. 0
10
20
30
40
50
60
0 5 10 15 20 25
GFR in Infants
GFR [ml/min/1.73
m2]
Age [days]
Guignard, J Pediatr 87:268-72, 1975
16. AKI: A Common, Serious
Problem
• 5% of all hospitalized patients, and up to 30% of patients in PICU
Stickle SH et al: Am J Kid Dis 45:96-101, 2005
17. Pediatric AKI: Recent Epidemiology
Patient Selection
• Reviewed all admissions to Texas Children’s Hospital from
January 1998 through June 2001
• Selected patients <20 years of age with ARF
• GFR by Schwartz < 75 ml/min/1.73m2 (n=254)
Stickle SH et al: Am J Kid Dis 45:96-101, 2005
18. Pediatric AKI: Recent Epidemiology
Pediatric ARF: Age Distribution
22%
15%
13%
34%
16%
0 to 30 d
1 to 12 mo
1 to 5 yr
6 to 14 yr
15 to 20 yr
Stickle SH et al: Am J Kid Dis 45:96-101, 2005
19. Pediatric AKI: Recent Epidemiology
Most Common ARF Causes
• ATN-Dehydration (21%)
• Nephrotoxic drugs (16%)
• Sepsis (11%)
• Unknown (14%)
• Primary Renal Disease (7%)
Patient Survival
• 176/254 patients (70%)
• 110/185 patients with ICU care (60%)
• 43/77 patients receiving renal replacement therapy (56%)
Stickle SH et al: Am J Kid Dis 45:96-101, 2005
21. - R = Risk for renal dysfunction
- I = Injury to the kidney
- F = Failure of kidney function
- L = Loss of kidney function
- E = End-stage renal disease
pRIFLE Criteria
Andreoli SP: Acute kidney injury in children. Pediatr Nephrol 2009
22. pRIFLE Criteria Estimated CrCl
(Schwartz)
Urine output
Early R (risk) ↓ 25% < 0.5 ml/kg/hr x 8 h
I (injury) ↓ 50% < 0.5 ml/kg/hr x 16 h
F (failure) ↓ 75% or eCCl <35
ml/min/1.73 m2
< 0.3 ml/kg/hr x 24 h/ anuria
Late L (loss) Renal failure > 4 weeks
E (end stage) Renal failure > 3 months
Pediatric RIFLE criteria
25. 1- Prerenal azotemia
a) Volume depletion (hypovolemia)
b) ↓ effective arterial pressure (shock)
c) ↓ effective circulating volume (heart failure)
26. 2- Intrinsic renal disease:
a) Glomerular (glomerulonephritis)
b) Tubulointerstitial: ATN, or interstitial pathology
c) Vascular (arterial or venous thrombosis)
1
2
Glomerular
Tubulointerstitial
3 Vascular
27. Examples of intrinsic renal diseases:
Glomerulonephritis: postinfectious GN, lupus nephritis, HSP
nephritis.
HUS is the most common cause in the USA.
Tumor lysis syndrome : spontaneous or chemotherapy-induced
cell lysis of lymphoproliferative malignancies
obstruction of the tubules by uric acid crystals
Acute interstitial nephritis due to hypersensitivity reaction to a
therapeutic agent or various infectious agents
Acute Tubular Necrosis (ATN)
32. Detailed History, physical examination and Chart review
are most important
Clinical Evaluation of AKI
Laboratory studies
CBC
Electrolytes
CBG (or VBG)
Diagnosis-specific Lab tests
33. Finding Pre-renal AKI Intrinsic AKI
UOsmol(mOsm/kg) >500 <350
USG >1020 <1010
UNa (mmol/d) <20 >40
FENa (%) <1 >2
Plasma BUN/Cr ratio >20 <10-15
Urine sediment Bland and/or nonspecific May show muddy brown
granular casts
FENa = [Urine Na/ Plasma Na] x [Plasma Cr/ Urine Cr] x 100
34. The Value of Urinalysis
Pre-renal
Intrinsic renal
Glomerular
ATN
AIN
Post-renal
Urinalysis
High specific gravity, normal or hyaline casts
Proteinuria, hematuria (RBC casts)
muddy brown casts, epithelial cells cast
Mild proteinuria, hematuria, WBC, WBC casts, eosinophils
Normal or hematuria, WBC, occasional granular casts
35. Documents the presence of one or two kidneys
Assesses renal size
Assesses renal parenchyma
Detects urinary tract obstruction
Detects occlusion of major renal vessels (Doppler)
Renal ultrasonography
Other imaging studies as indicated
36. Most commonly obtained in patients with:
1. Suspected glomerulonephritis.
2. In those with otherwise unexplained AKI.
Renal Biopsy
39. Biomarkers: AMI versus AKI
Period Acute Myocardial Infarction Acute Kidney Injury
1960s LDH
1970s CPK, myoglobin
1980s CK-MB
1990s Troponin T
2000s Troponin I
Multiple Therapies
50% ↓ Mortality
40. Period Acute Myocardial Infarction Acute Kidney Injury
1960s LDH Serum creatinine
1970s CPK, myoglobin Serum creatinine
1980s CK-MB Serum creatinine
1990s Troponin T Serum creatinine
2000s Troponin I Serum creatinine
Multiple Therapies
50% ↓ Mortality
Supportive Care
High Mortality
Needs early biomarkers of AKI to improve understanding, early
treatment and better outcomes
Biomarkers: AMI versus AKI
41. Role of Biomarkers in AKI
• Early prediction and diagnosis of AKI
• Identify the primary location of injury
• Pinpoint the duration and severity
• Identify the etiology of AKI
• Monitor response to intervention and treatment
Devarajan, Semin Nephrol 27:637-651, 2007
Devarajan, Contrib Nephrol 160:1-16 , 2008
46. A. Maintenance of electrolyte and fluid balance.
B. Avoidance of life-threatening complications.
C. Adequate nutritional support.
D. Treatment of the underlying cause.
Management Goals
47. If no evidence of volume overload or cardiac failure
Fluid challenge of IV NS , 20 mL/kg over 30 min
No void within 2-4 hr points to intrinsic or postrenal ARF
Vigorous fluid resuscitation may be needed in sepsis
? Diuretics if no void with adequate circulation (CVP ?).
? Renal dose of dopamine (2-3 μg / kg / min)
Management: FLUIDS
49. 1. Severe hyperkalemia (>7.0 mEq/L):
- electrocardiographic changes or peripheral muscle weakness
- can be life-threatening and requires immediate attention.
2. Acute management includes administration of:
IV calcium to stabilize the cardiac membrane;
and/or glucose/insulin infusion,
sodium bicarbonate, or beta agonists (promotes
extracellular K shift into the cells)
Kayexalate (an anion exchange resin): removes excess K
from the body.
Renal replacement therapy: if medical management fails
Hyperkalemia
50. 1. In children with AKI:
• impaired acid excretion
• increased acid production (shock and sepsis)
2. Sodium bicarbonate should only be administered with life-
threatening acidosis or hyperkalemia.
3. HCO3 > 12 mEq/L and/or arterial pH greater than 7.2 do not
require immediate intervention.
Acidosis
51. • Most often a result of hypervolemia.
• The choice of antihypertensive therapy:
The degree of hypertension and the clinical
presentation.
Hypertension
52. Adequate calories are needed to promote recovery
Renal replacement therapy if sufficient calories cannot be
achieved (patient with oliguria or anuria)
Patients with inappropriate nutrition have poorer prognosis.
Nutrition
53. Severe fluid overload unresponsive to management
Persistent hyperkalemia
Severe met.acidosis unresponsive to management
Neurologic symptoms (altered mental status, seizures)
BUN >100-150 mg/dL (or lower if rapidly rising)
Ca:PO4 imbalance, with hypocalcemic tetany
Nutritional support in a child with oliguria or anuria
Indications for dialysis in ARF
55. Depends upon the etiology, age, clinical presentation, and
status of the patient.
Hypotension and the need for inotropic support are
significant poor predictors for patient survival.
Worse prognosis (pt survival) in the context of multi-organ
failure.
Prognosis of AKI
57. Take Home Messages
AKI is a common and serious problem
All AKI are Not equal
The diagnosis of AKI is often delayed
Earlier recognition and treatment of AKI sequelae may
improve outcome
Novel biomarkers are providing tools for the early prediction
of AKI and outcomes, and for testing therapies
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This is a similar study performed in newborns by measuring inulin clearance. GFR approximately doubles in the first 2-4 weeks of life.
The rapid increase in GFR in early life is probably related to profound renal hemodynamic changes.
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With pRIFLE criteria, there are 2 phases of AKI; THE EARLY AND LATE. Early phase is subdivided into 3. Stage 1, ARR is defined as 25% loss of eGFR and/ or oliguria lasting for 8 hrs. Stage 2, AKI is 50% loss of GFR [or oliguria for 12 hr] and Stage 3, AKF is &gt;75% loss in GFR [and/ or anuria]. Less likely reversible is Renal Loss w/ AKF that lasted for 1 mo and regarded as irreversible is ESKD, AKF for more than 3 mo .
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