[5] Acute Kidney Injury Flashcards

1
Q

What is acute kidney injury defined as?

A

An abrupt deterioration in parenchymal renal function, which is usually but not always reversible over a period of days or weeks

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2
Q

Why can AKI be a medical emergency?

A

It can cause sudden, life-threatening biochemical disturbances

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3
Q

How is AKI usually recognised?

A

By reduced urine output and raising serum urea and creatinine

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4
Q

What are the risk factors for AKI?

A
  • Pre-existing CKD
  • Age
  • Male gender
  • Co-morbidities
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5
Q

What co-morbidities increase the risk of AKI?

A
  • Diabetes
  • CVD
  • Malignancy
  • Chronic liver disease
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6
Q

What are the common causes of AKI?

A
  • Sepsis
  • Major surgery
  • Cardiogenic shock
  • Other hypovolaemia
  • Drugs
  • Hepatorenal syndrome
  • Obstruction
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7
Q

What are the categories of causes of AKI?

A
  • Pre-renal
  • Renal
  • Post-renal
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8
Q

What happens in pre-renal AKI?

A

There is decreased perfusion of kidneys

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9
Q

What is the pathology in renal AKI?

A

Intrinsic renal disease

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10
Q

What happens in post-renal AKI?

A

Obstruction of urine

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11
Q

What are the causes of pre-renal AKI?

A
  • Hypovolaemia
  • Decreased cardiac output
  • Hypotension without hypovolaemia
  • Renal vasoconstriction
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12
Q

What can cause hypovolaemia?

A
  • Dehydration
  • Haemorrhage
  • D&V
  • Burns
  • Pancreatitis
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13
Q

What can cause decreased cardiac output?

A
  • Cardiogenic shock
  • MI
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14
Q

What can cause hypotension without hypovolaemia?

A
  • Cirrhosis
  • Shock
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15
Q

What can cause renal vasoconstriction?

A
  • NSAIDs
  • ACE inhibitors
  • Hepatorenal syndrome
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16
Q

What are the renal causes of AKI?

A
  • Glomerular disease
  • Interstitial disease
  • Vessel disease
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17
Q

What can cause glomerular disease?

A
  • Glomerulonephritis
  • Acute tubular necrosis
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18
Q

What can cause interstitial renal disease?

A
  • Drug reactions
  • Infection
  • Infiltration
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19
Q

What can cause vessel disease in the kidneys?

A
  • Vasculitis
  • Haemolytic uraemic syndrome
  • Thrombotic thrombocytopenic purpura
  • Disseminated intravascular coagulation
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20
Q

What % of renal parenchymal AKIs are due to acute tubular necrosis?

A

80-90%

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21
Q

What will lead to ischaemic ATN?

A

Almost any cause of AKI< if prolonged to a point where renal autoregulation fails

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22
Q

What does ATN usually result from if not ischaemic?

A

Direct tubular toxins

23
Q

What are some causes of ATN?

A
  • Haemorrhage
  • Burns
  • D&V
  • Pancreatitis
  • Diuretics
  • MI
  • Endotoxic shock
  • Hepatorenal syndrome
  • Pre-eclampsia
24
Q

What are the causes of post-renal AKI?

A
  • Obstruction with renal tract
  • Extrinsic compression
25
Q

What can cause obstruction within renal tract?

A
  • Stones
  • Renal tract malignancy
  • Strictures
  • Clots
26
Q

What can cause extrinsic compression post-renally?

A
  • Pelvic malignancy
  • Prostatic hypertrophy
  • Retroperitoneal fibrosis
27
Q

What are the diagnostic criteria for AKI?

A
  • Rise in creatinine >26μmol/L within 48 hours
  • Rise in creatinine 1.5x baseline within 7 days
  • Urine output <0.5mL/kg/hour for <6 consecutive hours
28
Q

Describe the progression of AKI?

A

In the early stages of AKI, there may not be any symptoms, other than possibly reduced urine production (but this is not always the case). however, someone with an AKI can deteriorate quickly, leading to symptoms

29
Q

What are the symptoms of AKI?

A
  • Nausea and vomiting
  • Dehydration
  • Confusion
  • High blood pressure
  • Abdominal pain
  • Slight backache
  • Oedema
30
Q

What is classified as a stage 1 AKI?

A
  • Serum creatinine >26.5μmol/L, or 1.5-1.9x baseline
  • Urine output <0.5mL/kg/h for 6-12 hours
31
Q

What is classified as a stage 2 AKI?

A
  • Serum creatinine 2.0-2.9x baseline
  • Urine output <0.5mL/kg/h for >12 hours
32
Q

What is classified as a stage 3 AKI?

A
  • Serum creatinine >353.6μm/L, or >3.0x baseline, or RRT
  • Urine output <0.3ml/kg/h for >24 hours, or anuria for >12 hours
33
Q

What is involved in the immediate management of an AKI?

A
  1. Assess for life-threatening complications
  2. Examine, including heart rate, BP, JVP, capillary refill, and bladder palpitation
  3. Treat hypovolaemia with fluid bolus of 250-500mL, until volume repleted. If 2L given without response, seek expert help
  4. Monitor
  5. Investigate
  6. Support
34
Q

How do you assess for life threatening complications in AKI?

A
  • Check NEWS
  • Assess for pulmonary oedema
  • Perform urgent potassium measurement using VBG
35
Q

What should you do if NEWS is high in AKI?

A

Consider critical care referral

36
Q

What should you do if pulmonary oedema is present in AKI?

A

Early referral to renal, as may need dialysis

37
Q

When should you treat hyperkalaemia in AKI?

A

If >6.5mmol/L, or any ECG changes

38
Q

What montioring is done in AKI?

A
  • Fluid balance
  • Potassium
  • Observation at a minimum of every 4 hours
  • Measure lactate if signs of sepsis
  • Daily creatinine
39
Q

What should be considered in order to accurately measure fluid balance in AKI?

A

Urinary catheter and hourly urine output

40
Q

How often should you check potassium in AKI?

A

You should check response to any treatment, and at least daily until creatinine falls

41
Q

How long should you measure daily creatinine in AKI?

A

Until it reduces

42
Q

How should AKI be investigated?

A
  • Urine dipstick, and quantification of any proteinuria
  • USS
  • Check LFTs and platelets
  • Investigate for intrinsic renal disease
43
Q

What might proteinuria or haematuria suggest in AKI?

A

Intrinsic renal disease

44
Q

How quickly should USS be performed in AKI?

A

Within 24 hours, unless cause obvious or improving

45
Q

What do small kidneys on USS indicate in AKI?

A

CKD

46
Q

What does asymmetry on USS indicate in AKI?

A

Renal vascular disease

47
Q

What do poor liver function tests indicate in AKI?

A

Hepatorenal syndrome

48
Q

What should be done if platelets are low in AKI?

A

Blood film for haemolysis

49
Q

How should you investigate for intrinsic renal disease in AKI?

A
  • Immunoglobulins
  • Paraprotein
  • Complement
  • Autoantibodies
50
Q

What supportive treatment should be given in AKI?

A
  • Treat sepsis
  • Stop nephrotoxic medications
  • Stop drugs that may increase complications
  • Check all drug doses are suitable for renal impairment
  • Consider gastroprotection with histamine antagonist or PPI, and nutritional support
  • Avoid radiological contrast
51
Q

Give 4 examples of nephrotoxic medications

A
  • NSAIDs
  • ACE inhibitors
  • ARBs
  • Aminoglycosides
52
Q

What drugs might cause complications in AKI?

A
  • Diuretics
  • Metformin
  • Anti-hypertensives
53
Q

When should you refer to renal team in AKI?

A
  • AKI not responding to treatment
  • AKI with complications, including hyperkalaemia, acidosis, or fluid overload
  • AKI with difficult fluid balance, e.g. hypoalbuminaemima, heart failure, or pregnancy
  • AKI due to possible intrinsic renal disease
  • AKI with hypertension