Renal disease in a child: Acute Renal Failure Flashcards

1
Q

Define acute renal failure.

A

A significant deterioration in renal function occurring over hours or days, resulting in increased plasma urea, creatinine and oliguria. Complete recovery of renal function usually occurs within days/weeks.

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2
Q

What are some pre-renal causes of acute renal failure?

A
  • Hypovolaemia: Haemorrhage, GI losses, DKA, burns, diarrhea, septic shock.
  • Cardiac failure: Severe coarctation, hypoplastic left heart, myocarditis.
  • Hypoxia: Pneumonia, RDS.
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3
Q

What are some intrinsic renal causes of acute renal failure?

A
  • Acute tubular necrosis (ATN) (80% of intrinsic renal causes) due to circulatory compromise or nephrotoxic drugs (paracetamol, aminoglycosides)
  • Acute GN
  • Acute interstitial nephritis: Infection, drugs: NSAIDS, frusemide, penicillin
  • Small/large vessel obstruction: Renal artery/vein thrombosis, vasculitis, HUS, TTP
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4
Q

What are some post-renal (obstructive) causes of acute renal failure?

A
  • Neuropathic bladder: May be acute in transverse myelitis, spinal trauma.
  • Stones: Bilateral pelvicureteric junction or ureteral.
  • Urethral prolapse of bladder ureterocele
  • Iatrogenic: Catheters, stents, nephrostomy or surgery
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5
Q

What is the pathophysiology of acute tubular necrosis?

A

Macro: Enlarged kidneys with pale cortex.

Micro: Swelling and necrosis of the tubular cells, interstitial oedema with macrophage and plasma cell infiltration.

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6
Q

Summarise the epidemiology of acute renal failure.

A

0.8/100,000 children

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7
Q

What are symptoms of acute renal failure?

A

Vomiting

Anorexia

Oliguria

Convulsions

Previous sore throat and fever (post-streptococcal GN)

Bloody diarrhoea and progressive pallor (HUS)

Drug history

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8
Q

What are signs of acute renal failure?

A

Assess intravascular volume status: Volume depleted (cool peripheries,tachycardia, postural hypotension) or overloaded (oedema, weight gain, pulmonary oedema)

Septic

Obstruction

Examine abdomen for palpable bladder

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9
Q

What are appropriate investigations for acute renal failure?

A

Bloods: Decreased Hb (hypovolaemia/haemorrhage), increased WCC, increased CRP, blood cultures (sepsis), increased urea, increased creatinine, increased potassium, increased phosphate, decreased calcium, decreased magnesium, LFTs, venous capillary blood gas, clotting (DIC), ASOT (post-streptococcal GN)

Blood film: HUS/TTP (RBC fragmentation).

Urine: Urinalysis for blood, protein (GN), glucose (interstitial nephritis), microscopy for casts (GN), urine Na+, urea, creatinine, osmolality to differentiate between pre-renal and instrinsic renal failure

ECG: Signs of hyperkalaemia; tall tended T wave; small or absent P waves; increased P-R interval; widened QRS complex; sine wave pattern; asystole.

CXR: Signs of pulmonary oedema

Renal USS: In ARF, kidneys appear normal or increased in size and echogenicity, may detect stones or clot in renal vein thrombosis (RVT)

Renal biopsy: If diagnosis has not been determined

Monitor: Daily U&E, temperature, PR, RR, BP, O2 saturation, strict input/output (need to catheterize), daily weights

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10
Q

What is the management for acute renal failure?

A

Resuscitate: Especially in pre-renal causes of ATN

Fluids: Allow insensible losses (400 ml/m2) + ml for ml replacement of urine output in acute phase

Treat the cause

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11
Q

What are indications for acute dialysis?

A
  • Severe extracellular fluid volume overload, increase BP, pulmonary oedema not responding to diuretics
  • Severe increase in K+; not responding to medical treatment
  • Severe systematic uraemia
  • Severe metabolic acidosis, not controllable with IV bicarbonate
  • Removal of toxins (drugs, poisons)
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12
Q

What are complications associated with acute renal failure?

A

Heart failure and pulmonary oedema (volume overload)

GI bleeding (gastric ulceration and platelet dysfunction)

Muscle wasting due to hypercatabolic state

Uraemic encephalopathy

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13
Q

What is the prognosis of acute renal failure?

A

Depends on the causative factor.

Recovery of renal function following ARF is most likely following pre-renal causes, HUS, ATN, acute interstitial nephritis or uric acid nephropathy.

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