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Acute renal failure
Dr.Nariman Fahmi
pediatric / 2013
Objectives
• Introduction
• Defintion
• Classification
• management
To function properly
kidneys require:
• Normal renal blood flow
• Functioning glomeruli and tubules
• Clear urinary outflow tract – for drainage and elimination of formed
urine from the body.
ARF - definition
• An abrupt fall in GFR over a period of minutes to days with rapid & sustained rise in nitrogenous waste products in blood.
(Rate of production of metabolic waste exceeds the rate of renal excretion)
definition
Sudden loss of the ability of the kidneys to excrete wastes,
concentrate urine and conserve electrolytes
Definitions
• Oligurea
• Low urine output
• < 300 ml/m2/day
• Anurea
• No urine output
Causes of AKF
• Prerenal : renal hypoperfusion
• Renal (Intrinsic) :
– Glomerular
– Tubular
– Vascular
– Interstitial
• Post renal: obstruction
injury
Generalized or localized
reduction in RBF
Hypovolaemia Haemorrhage
Volume depletion
( vomiting,
diarrhoea,
burns)
Hypotension Cardiogenicshock
(sepsis,
anaphylaxis)
Oedema
states Cardiac failure
Hepatic cirrhosis
Nephrotic
syndrome
Renal
Hypoperfusion
NSAIDs
ACEI / ARBs
RAS /occlusion
Hepatorenal
syndrome
Reduced GFR
PRE-RENAL (Hemodynamic) AKI
PRERENAL AKI
Renal / Intrinsic AKI
Tubular Glomerular Vascular Interstitial
ATN
Ischemia
Toxins
Ac. Interstitial
nephritis
Drug induced -
NSAIDs,
antibiotics
Infiltrative -
lymphoma
Granulomatous-
tuberculosis
Infection related -
post-infective,
pyelonephritis
Vascular
occlusions
-Renal artery
occlusion
-Renal vein
thrombosis
Ac.GN
post-infectious,
SLE,
ANCA associated,
Henoch-Schönlein purpura
,
Thrombotic microangiopathy
TTP
HUS
N Engl J Med 1996;334 (22):1448-60
Principal POST-RENAL causes of AKI
Intra-luminal •Stone,
•Blood clots,
•Papillary
necrosis
•Pelvic
malignancies
•Retroperitonea
l fibrosis
Intrinsic
Intra-mural •Urethral stricture,
• Bladder tumour,
• Radiation fibrosis
Extrinsic
Post-renal Urinary outflow tract obstruction
Careful history may aid in defining the cause of
renal failure
S.&S.
Oligurea or anuria
Fluid retention Ankle ,legs swelling
Changes in mental status
Drawsiness , lethargy, confuion ,coma
Seizures
Vomiting
hypertension
Factors that suggest chronicity include –
Long duration of symptoms,
Nocturia,
Absence of acute illness, anaemia,
hyperphosphatemia, and hypocalcaemia,
On examination : note state of
dehydration
Is the patient euvolaemic?
Pulse,
JVP/CVP,
blood pressure,
Fluid challenge
Has obstruction been excluded?
Complete anuria
Palpable bladder
Renal ultrasound
Hilton et al, BMJ 2006;333;786-790
What investigations are most useful in ARF?
Urinalysis:
Dipstick for blood, protein, or both - Suggests a
renal inflammatory process
Microscopy for cells, casts, crystals - Red cell casts
diagnostic in glomerulonephritis
Hilton et al, BMJ 2006;333;786-790
RBCs
•Dysmorphic red blood cells suggest glomerular injury.
Red blood cell cast
Marker of glomerular injury
Granular cast
Biochemistry
Serial blood urea, creatinine, electrolytes,
Blood gas analysis, serum bicarbonate –
Important metabolic consequences of
ARF include hyperkalaemia, metabolic
acidosis, hypocalcaemia,
hyperphosphataemia
• Radiology
• Renal ultrasonography
– For renal size, symmetry, evidence of
obstruction
Treatment
The goal is to
• 1-identify any reversible causes
• 2- preventing excess accumulation of
fluids and wastes
Hospitalizations is required for treatment
and monitoring
• Antibiotics may be used to treat infection
• Diuretics may be used to remove fluid
Control dangerous hyperkalemia
• S.k more than 6 meq/l
• 1- calcium gluconate 10% solution
• 2-sodium bicarbonate 7.5%solution
• 3-Glucose 50 % with insulin1unit/5 g glucose
• 4-B receptor agonist
• 5-Oral or rectal potassium exchange resine(kayexalate)
• Hyponatremia is most commonly a dilutional disturbance
• Nacl (meq/L) required =0.6(BW Kg)x {125- serum sodium (meq/L)}
• Nutrition in acute renal failure
• sodium, potassium, and phosphorus should be restricted.
• Protein intake should be restricted
Hypertension
Agent Dose Onset Action Complications
Hydralazine 0.2 to 15 mg/dose
• Nifedipine 0.25-0.5 mg/kg sublingual
• Frusemide 1-3mg/kg over 15min 0.1-1mg/kg/hr
Diazoxide 5 mg/kg (max 300) IV bolus 3-5 min
• gastrointestinal bleeding
• Neurological symptoms
• anemia of ARF is generally mild
(hemoglobin 9–10 g/dL) and primarily
results from volume expansion
(hemodilution )
dialysis
Used to remove excess waste and fluids
Indications
1- uncontrollable fluids overload or hypertension
2- uncontrollable acidosis
3- uncontrollable electrolyte disturbances
4-pericarditis
5- change in mental status
6-anuria
7-uncontrollable accumulations of nitrogen waste
products
Thank you