Acute Kidney Injury Flashcards

1
Q

Definition of acute kidney injury?

A

Sudden acute drop in kidney function

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2
Q

How is acute kidney injury diagnosed?

A

Measuring serum creatinine

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3
Q

What is AKI characterized by?

A

-Rapid increase in blood urea & creatinine concentration caused by decreased glomerular filtration rate

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4
Q

Criteria for AKI?

A
  • Rise in creatinine of >26.4micromol/L in 48 hours
  • Rise in creatinine of >50%
  • Urine output of <0.5ml/kg/hour for more than 6 hours
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5
Q

Who can commonly get AKI?

A

Common for patients already in hospital

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6
Q

Risk factors for AKI?

A
  • CKD
  • Heart fialure
  • Diabetes
  • Liver diseasse
  • Older age (>65)
  • Cognitive impairment
  • Nephrotoxic medications: lithium, haldol
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7
Q

Classifying causes of acute renal injury?

A

Pre-renal
Renal/Intrarenal
Post-renal

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8
Q

Which is the most common type of cause of AKI?

A

Pre-renal

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9
Q

What is pre-renal caused AKI due to?

A

Inadequate supply to kidneys reducing filtration of blood

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10
Q

What can cause the inadequate blood supply resulting in pre-renal AKI?

A
  • Dehydration
  • Hypotension (shock/volume depletion)
  • Heart failure (reduced effective circulating volume)
  • Renal artery stenosis
  • Renal hyperfusion
  • Pharmacological (NSAIDs, ACEi)
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11
Q

What is renal AKI?

A

Where intrinsic disease in kidney is leading to reduced filtration of blood

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12
Q

Possible causes of Renal AKI?

A
  • Ischaemic injury
  • Nephrotoxic injury
  • Immune-mediated injury
  • Vasculitis/vascular disease
  • Interstitial nephritis
  • Glomerulonephritis
  • Acute tubular necrosis
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13
Q

What is the cause of post-renal AKI?

A

Obstruction to outflow of urine from kidney, causing back-pressure into kidney and reduced kidney function

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14
Q

What is the cause of post-renal AKI called?

A

Obstructive uropathy

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15
Q

What can renal obstruction be caused by?

A
  • Kidney stones
  • Blood clots
  • AAA
  • Masses eg cancer (usually retroperitoneal)
  • Ureter or ureteral strictures
  • Enlarged prostate/prostate cancer
  • Bladder issues (malignancy, blood clot)
  • strictures
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16
Q

Signs/symptoms of AKI?

A

Non-specific:

  • Anorexia, wt loss, fatigue, lethargy
  • N/V
  • Itch
  • Fluid overload

Signs:

  • Uraemia including itch
  • Pericarditis
  • Oliguria
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17
Q

What may pre-renal AKI presnet with?

A
  • Hypovolaemia

- Hypotension

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18
Q

What does hypotension/hypovolaemia present as?

A
  • Thirst
  • Dizziness
  • Weakness
  • Diarrhoea
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19
Q

Investigations for AKI?

A
  • Urinalysis: protein, blood, glucose, nitrates
  • U&Es
  • FBC and coags
  • Immunology: ANA, ANCAM, GBM
  • Protein electrophoresis
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20
Q

How many stages in KDIGO staging and what is it?

A

3 stages

Kidney disease Improving Global Outcomes criteria

21
Q

Stage 1 KDIGO?

A
Serum Creatinine:
-Increase >26 micromol/L within 48 hours 
OR 
-1.5 fold increase in serum creatinine 
OR 
-
-GFR decrease 

or

Urine output criteria:
- <0.5ml’Kg/h for 6 hours

22
Q

Stage 2 KDIGO?

A

Serum creatinine criteria:

  • 2 fold increase in serum creatinine
  • GFR decrease >50%

OR

Urine output criteria:
-<0.5ml/Kg/h for >12 hours

23
Q

Stage 3 KDIGO?

A
Serum creatinine criteria:
- 3 fold increase in serum creatinine 
OR
-Increase >354 micromol/L 
OR 
-GFR decrease >75% 
OR 
started on renal replacement therapy 

OR

Urine output criteria:
- <0.3mL/Kg/hr for >24 hours of 12 hours for anuria

24
Q

Prevention of CKD?

A
  • Avoiding nephrotoxic meds where possible

- Ensuring adequate fluid input in unwell patients

25
Q

First step to treat AKI?

A

Treat underlying cause

26
Q

How to treat underlying cause in pre-renal AKI?

A

Fluid rehydration
fluid challenge for hypovolaemia
- crystalloid (0.9% NaCl)// colloid - don’t use dextrose/Harmans (K)
- bolus of fluid - reassess - repeat
- if 1000 ml & no improvement - seek help

27
Q

How to treat underlying cause for drug induced AKI?

A

Stop nephrotoxic meds (NSAIDs and antihypertensives) that reduce filtration pressure (ACEis)

28
Q

How to treat underlying cause in Post-renal AKI?

A

Relieve obstruction eg insert catheter for enlarged prostate, nephroplasty
refer to urology if ureteric stenting required

29
Q

How to manage fluids?

A

Hypovolaemia: fluid boluses (250-500ml crystalloid)
Hypervolemia: Diuretics?

30
Q

What does hyperkalaemia predispose to?

A

Cardiac arrhythmias

31
Q

What are patients with AKI susceptible to ?

A

Hyperkalaemia

32
Q

Treating hyperklamiea?

A

IV calcium gluconate

33
Q

What is the renal replacement therapy of choice?

A

Haemodialysis

34
Q

Indications for haemodialysis?

A
A: Acidaemia 
E: Electrolytes (Hyperk)
I: Ingestion/toxins
O: Overload (fluid)
U: Uraemia and uraemic complications
35
Q

Complications of AKI?

A
  • Hyperkalaemia
  • Fluid overload, heart failure , pulmonary oedema
  • Metabolic acidosis
  • Uraemia can–> encephalopathy or pericarditis
36
Q

What tests can diagnose cause of AKI?

A
  • Urinalysis
  • FBC
  • Renal tract imaging
  • Renal biopsy
37
Q

How can AKI be prevented?

A

Miantaining adequate BP
Volume status
Avoiding nephrotoxic meds

38
Q

Nephrotoxic drugs are?

A
  • NSAIDs
  • ACEis
  • ARBs
39
Q

a definition of pre-renal AKI?

A

reversible volume depletion leading to - oliguria <0.5 ml/kg/hr and increase in creatinine

40
Q

what is the pathophysiology of pre-renal AKI?

A
hypovolaemia 
- haemorrhage 
- D&V
- burns 
hypotension 
- cardiogenic shock 
- sepsis 
- anaphylaxis 
renal hypoperfusion (<20% CO)
- NSAID/ COX2 
- hepatorenal syndrome 
- ACEi/ARBs 
  decreased renal perfusion activates RAAS to try and increase GFR
  if ACEi: can't activate RAAS - vasodilation of efferent arteriole
41
Q

what is the prognosis of pre-renal AKI?

A

if untreated - acute tubular necrosis

  • commonest hospital AKI
  • sepsis, severe dehydration
  • rabdomyolysis and drug toxicity
42
Q

what are the possible pathogenesis of renal AKI?

A

vascular - vasculitis: GPA, MPA, renovascular disease
glomerulus - glomerulonephritis
interstitial nephritis - drugs: NSAIDs, penicillin, infection: TB, systemic: sarcoid
tubular injury - ischaemia - renal hypoperfusion, drugs: gentamicin, contrast and rhabdomyolysis

43
Q

what is the presentation of renal AKI?

A

constitutional: anorexia, fatigue, lethargy
N&V
uraemia - itch
fluid overload - oedema, SOB, HTN, effusion
oliguria

44
Q

how is renal AKI managed?

A
investigations 
U&E – marker of renal function: Na, Ur, Cr
FBC &Coagulation
o abnormal clotting – sepsis
o anaemia – EPO
urinalysis – haematoproteinuria
USS – obstruction
immunology – ANA (SLE), ANCA, GBM
Protein electrophoresis & BJP – myeloma

Treatment
establish good perfusion pressure: fluid resuscitation - inotropes, vasopressors
treat underlying cause: antibiotics if sepsis
stop nephrotoxics
dialysis if anuric & uraemia

45
Q

hyperkalaemia

A

normal K 3.5- 5.0
hyperkalaemia >5.0
life-threatening >6.5

46
Q

how is hyperkalaemia investigated?

A

muscle weakness
ECG
- peaked T waves (6-7mmol)
- flattened p wave, prolonged PR, depressed ST, peaked T wave (7-8 mmol)
- atrial stand still, prolonged QRS, peaked T wave (8-9 mmol)
- sine-wave (>9 mmol)

47
Q

how is hyperkalaemia managed?

A

cardiac monitor & IV access
protect myocardium: 10ml 10% calcium gluconate (2-3 min)
move K+ back into cells
- insulin-actrapid 10 units with
- 50ml 50% dextrose (30 min)
- salbutamol nebs (90 min)
prevent GI absorption - calcium resonium (NOT in acute setting)

48
Q

indications for haemodialysis

A

hyperkalaemia (>7/>6.5 unresponsive to medical therapy
severe acidosis pH <7.15
fluid overload
urea > 40 (pericardial rub/effusion)

49
Q

drugs to avoid in AKI

A
NSAID
ACEi/ARB
diuretics
gentamicin
contrast
trimethoprim – hyperkalaemia
K+ sparing diuretics