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Acute kidney injury Flashcards

1
Q

What is AKI

A
  • A rapid(within hours to days) fall in glomerular filtration rate (GFR) which impedes the kidney’s normal functions
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2
Q

AKI stage 1 serum creatinine criteria

A
  • Increase in serum creatinine of 26 micromol/litre or more within 48 hrs or 1.5-2 fold increase from baseline
  • Less than 0.5 ml/kg/hour urine for more than 6 hrs
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3
Q

AKI stage 2 serum creatinine criteria

A
  • Increase in serum creatinine to more than 2 to 3-fold from baseline
  • Less than 0.5 ml/kg/hour for more than 12 hrs
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4
Q

AKI stage 3 serum creatinine criteria

A
  • Increase in serum creatinine to more than 3-fold from baseline OR serum creatinine more than 354 micromol/litre with an acute increase of at least 44 micromol/litre
  • Less than 0.3 ml/kg/hour for 24 hours or anuria for 12 hrs
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5
Q

AKI stage 1 urine output criteria

A

Less than 0.5 ml/kg/hour for more than 6 hours*

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6
Q

AKI stage 2 urine output criteria

A

Less than 0.5 ml/kg/hour for more than 12 hours

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7
Q

AKI stage 3 urine output criteria

A

Less than 0.3 ml/kg/hour for 24 hours or anuria for 12 hours

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8
Q

What is creatinine

A
  • A normal product of muscle turnover
  • Non-toxic
  • Transported by the blood and excreted by the kidneys
  • Used as a surrogate marker for glomerular filtration.
  • Less filtration => less creatinine removed => a creatinine rise
    GFR is estimated from creatinine results
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9
Q

Urine output criteria - oliguria

A

<0.5ml/kg/hr urine output

Usually <500ml/24 hrs in adults

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10
Q

Urine output criteria - anuria

A
  • officially would mean no urine output

- Softly defined as <100ml/24 hrs

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11
Q

AKI natural time course phases

A 
Four Phases
Onset phase
Oliguric/Anuric phase
Polyuric/Diuretic phase
Recovery phase
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12
Q

AKI - onset phase

A
  • Common triggering events: significant blood loss, burns, fluid loss, diabetes insipidus
  • Renal blood flow 25% of normal
  • Tissue oxygenation 25% of normal
  • Urine output below 0.5 ml/kg/hr
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13
Q

AKI - onset phase duration

A

hours to days

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14
Q

AKI - oliguric(anuric) phase

A
  • Urine output below 400 ml/day, possibly as low as 100 ml/day
  • Increases in blood urea nitrogen (BUN) and creatinine levels
  • Electrolyte disturbances, acidosis, and fluid overload(from kidney’s inability to excrete water)
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15
Q

AKI - oliguric phase duration

A
  • 8-14 days or longer, depending on nature of AKI and dialysis initiation
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16
Q

AKI - diuretic phase

A
  • Occurs when cause of AKI is corrected
  • Renal tubule scarring and edema
  • Increased glomerular filtration rate (GFR)
  • Daily urine output above 400 ml
  • Possible electrolyte depletion from excretion of more water and osmotic effects of high BUN
17
Q

AKI - diuretic phase duration

A
  • 7-14 days
18
Q

AKI - recovery phase

A
  • Decreased edema
  • Normalisation of fluid and electrolyte balance
  • Return of GFR to 70% or 80% of normal
19
Q

AKI - recovery phase duration

A
  • several months to 1 yr
20
Q

Normal K+ levels

A

> 6.0 = bad

> 6.5 = medical emergency

21
Q

ECG features of hyperkalaemia

A
  • Reduced P wave with widened QRS complex
  • Tented T wave
  • ‘Sine wave’ pattern (pre-cardiac arrest)
22
Q

Symptoms of fluid overload

A
  • Breathlessness
  • Orthopnea
  • Limb swelling
23
Q

Danger of fluid overload in AKI

A

The danger = pulmonary oedema -> severe tissue hypoxia

If your patient is oliguric/anuric – they won’t be able to get rid of this excess water

24
Q

Indications for dialysis

A
  • Refractory hyperkalaemia
  • Pulmonary oedema
  • Refractory acid/base disturbance
  • Uraemic complications (coma, pericarditis)
25
Q

Pre-renal causes of AKI

A

Decrease in perfusion pressure resulting in ischaemia or infarction

  • Bleeding
  • Septic shock
  • Dehydration
  • MI
  • Iatrogenic
  • Renal artery stenosis
26
Q

Renal causes of AKI

A

Direct toxic effects

  • Drugs
  • Calcium and other metals

Overproduction leading to blockage of the tubules
- Rhabdomyolysis, myeloma

Inflammation in the kidney
- GN, interstitial nephritis, ATN

27
Q

Post-renal causes of AKI

A

Plumbing problem/outflow obstruction:

  • Stones
  • Ureteric/urethral strictures
  • BPH
  • Prostate cancer
  • Urinary retention e.g. neurogenic, constipation
28
Q

Who is at risk of AKI - chronic

A 
Elderly
CKD
Cardiac Failure
Liver disease
Diabetes
Vascular disease
Background nephrotoxic medications
29
Q

Risk of AKI - acute risk

A

S - Sepsis and hypoperfusion
T - Toxins
O - Obstruction
P - Parenchyma

30
Q

How do your predict/prevent AKI

A

The 4 ‘M’s
Monitor
Obs/NEWS, regular blood tests, fluid balance charts, pathology alerts

Maintain Circulation
Hydration, resuscitation, oxygenation

Minimise Kidney Insults
Nephrotoxic meds, surgery, contrast, hospital acquired infection

Manage the acute illness
Sepsis, heart failure, liver failure

31
Q

AKI - red flags in history

A 
Haemoptysis
Rashes
Joint pain/swelling
ENT – crusting of nose/acute hearing impairment
Significant acute limb swelling
Noticable urine frothiness
Jaundice
32
Q

Initial fluid assessment

A 
Focused history - Is the patient thirsty?
Capillary refill time
Mucus Membranes
Skin turgor
Pulse rate
BP (relative and postural)
Respiratory rate
Central vs. Peripheral temp
JVP
Lung auscultation
Oedema – peripheral and sacral
CXR – pulmonary oedema/infiltrates
Fluid balance charts/urine output
Invasive methods – catheter, arterial line, central line
33
Q

Drugs to avoid in AKI

A 
ACE inhibitors
Angiotensin Receptor Blockers
NSAIDS: ibuprofen, diclofenac, naproxen
Any diuretics
Metformin (theoretically)
34
Q

Causes of polyuria

A

Is a known and common phase of AKI of any cause
Post relief of obstruction
Diabetes mellitus
Pscyhogenic
Beer potomania
Rare endocrine causes (e.g. diabetes insipidus)

35
Q

Management of polyuria

A

Encourage the patient to drink
Depending on your assessment of fluid balance
Provide iv fluids to match the output+/- additional input if dry
Once renal function is beginning to improve reduce to 75% of urine output

302/308 (22 decks)

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