Acute Kidney Injury Flashcards by Peter Savage

Definition of Acute Renal failure?

Rapid loss of GFR and tubular function - hours to days
Urea/creatinine retention
Oliguric/non-oliguric

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What is the biochemical definition of acute renal failure?

Serum creatinine ↑:
>26.5umol within 48hrs
or
>1.5x baseline within 7 days
and
Urine volume <0.5ml/kg/h for 6hrs

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How is AKI stage 1 defined?

Serum creatinine ↑:
>26.5umol within 48hrs
or
>1.5x baseline within 7 days
and
Urine volume <0.5ml/kg/h for 6hrs

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How is AKI stage 2 defined?

Serum creatinine ↑:
2-3x baseline
and
Urine volume <0.5ml/kg/h for 12hrs

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How is AKI stage 3 defined?

3x baseline
or 
Increase to >354umol
or
Initiation of RRT
and 
<0.3ml/kg for 24hrs
or
Anuria for 12hrs

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How common is AKI?

1 in 7

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What factors can increase the risk of AKI?

Comorbidities

Old Age

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How does AKI present?

AEIOU
A - acidosis
E - electrolyte disturbance
I - intoxication
O - overload
U - Uraemia

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What is the mortality in dialysis-requiring AKI?

45-70%

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What is the mortality in non-dialysis requiring AKI?

AKI 1 - 8%
AKI 2 - 25%
AKI 3 - 33%

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What are the long term outcomes of AKI?

Death
CKD
Dialysis
CV events

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What are the main types of AKI?

Pre-renal (blood flow to kidney)
Renal (intrinsic)
Post-renal (obstruction of urine)

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What are the causes of pre-renal AKI?

Volume depletion
Hypotension
Shock
Congestive HF
Liver failure
Arterial occlusion
Vasomotor

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What drugs can cause vasomotor pre-renal AKI?

NSAIDs

ACEi

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What are the causes of intrinsic renal AKI?

Acute Tubular Necrosis
Toxins
Acute interstitial nephritis
Acute glomerulonephritis
Myeloma
Intra-renal vascular obstruction

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Which toxins are commonly associated with intrinsic AKI?

Amphotericin, aminoglycosides, NSAIDs
Radiocontrast (iodinated)
Rhabdomyolysis 
Snake venom
Heavy metals
Mushrooms

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What are the causes of post-renal AKI?

Obstruction
Intraluminal
Intramural
Extramural

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What are the intralumal causes of post-renal AKI?

Calculus
Clout
Sloughed papilla

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What are the intramural causes of post-renal AKI?

Malignancy
Ureteric stricture
Radiation fibrosis
Prostate disease

What are the extramural causes of post-renal AKI?

RPF

Malignancy

What is the course of acute ischaemic renal injury?

Initiation
Maintenance (established parenchymal damage, maximally oliguric, 1-2 wks)
Recovery

What is the cause of excessive recovery diuresis?

GFR recovering faster than tubule resorptive capacity

How does radiocontrast nephropathy present?

AKI following iodinated contrast administration
Transient renal dysfunction
72hr resolution
May be permanent

What are the risk factors for radiocontrast nephropathy?

DM
Renovascular disease
Impaired renal function
Paraprotein
Large volume of contrast

What is multiple myeloma?

Monoclonal proliferation of plasma cells producing excess Ig, light chains

How does myeloma typically present?

``` Anaemia Back pain Weight loss Fractures Infections Cord compression Marked elevated ESR Hypercalcaemia ```

Myeloma is common in who?

the elderly

How is myeloma diagnosed?

Bone marrow aspirate Serum paraprotein Urinary Bence-Jones protein Skeletal survey

How does renal failure present in myeloma?

``` Cast nephropathy Light chain nephropathy Amyloidosis Hypercalcaemia Hyperuricaemia ```

What blood tests should be performed in suspected AKI?

``` FBC U&E Bicarb LFTs Clotting Blood gas (ANCA/Ig/C3,C4) ```

What urine tests should be performed in suspected AKI?

Urine dip Urine PCR Urine bence jones protein

What are the risk factors for AKI?

``` Age >75 Previous AKI HF Liver disease CKD DM Vascular disease ```

What are the AKI risk events?

``` Sepsis Toxins Hypotension Hypovolaemia Major surgery ```

What should you consider in patients with one or more risk event/factor?

``` STOP S - sepsis T - Toxins O - Optimise BP/volum P - prevent harm ```

What steps should be taken to prevent AKI?

``` Avoid dehydration Avoid nephrotoxins Review clinical status, U&E, fluid balance Hold medications Treat sepsis ```

What should the next step be in sepsis?

``` Sepsis 6 Blood cultures Urine output monitoring, U&E Fluids Antibiotics Lactate O2 saturation ```

What should be considered in hypotensive patients?

Withdraw: - Antihypertensives - Diuretics Vasopressors

What are the insensible losses of water in the body?

Skin | Lungs

What ECG changes are seen in hyperkalemia?

``` Peaked, tented T waves P-wave widens then disappears PR lengthens Prolonged QRS Bradycardia High grade AV block ```

How is Hyperkalemia treated?

``` Stabilise Myocardium - Calcium Gluconate Shift K+ intracellularly - Insulin-dextrose - Salbutamol Remove - Diuresis - Dialysis - Anion exchange resins ```

What is the antidote to morphine?

Naloxone

What is the antidote to digoxin?

Digibind

What are the indications for dialysis in AKI?

``` Acidosis (↓HCO3-) Electrolytes (↑K+) Intoxication Overload (Pulmonary oedema) Uraemia (pericarditis) ```

What are the advantages of haemodialysis?

Fast solute/volume removal Fast correction of electrolytes Efficient for hypercatabolic patients

What are the disadvantages of haemodialysis?

Haemodynamic instability Concern with hypotension Fluid removal only during short treatment time

What are the advantages of continuous therapy?

Slow removal = greater haemodynamic stability | Less fluctuation in volume/solute control

What are the disadvantages of continuous therapy?

Continuous anticoagulation Delay weaning Hypercatabolic Pt - less clearance