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