Renal - Acute Kidney Injury Flashcards

1
Q

What is the definition of acute kidney injury?

A

An acute drop in kidney funciton from the patient’s baseline of normal.

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2
Q

How is AKI diagnosed?

A

By measuring the patient’s serum creatinine

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3
Q

What is the NICE criteria for AKI?

A

Urine output of <0.5ml/kg/hour for over 6 hours

Rise in creatinine of >50% in 7 days OR rise in creatinine of >25 micromol/L in 48 hours

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4
Q

List some risk factors for developing an AKI

A
Nephrotoxic medications
Heart failure
Liver disease
Dehydration
Sepsis
Old age
CKD
Diabetes
Contrast medium in CTs
Cognitive impairment
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5
Q

How can we differentiate the causes of Acute Kidney injury?

A

They will either be
Pre-renal
Renal
Post Renal

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6
Q

What is the most common form of AKI

A

Pre renal

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7
Q

How does pre renal AKI occurt?

A

There is reduced perfusion of the kidneys due to an inadequate blood supply

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8
Q

List the main causes of pre-renal AKI

A

Dehydration
Hypotension / shock
Heart failure
(Renal artery stenosis)

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9
Q

Define Renal AKI:

A

The intrinsic disease in the kidneys has led to a reduced filtration of blood

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10
Q

What are the causes of a renal AKI?

A

Glomerulonephritis
Acute Tubular necrosis
Interstitial nephritis

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11
Q

Describe the physiology of how a post renal AKI occurs?

A

There is an obstruction to the outflow from the kidney which leads to a back pressure into the kidney, reducing the kidney function.
AKA obstructive uropathy

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12
Q

List some causes of post renal AKI:

A

Kidney stones
Ureter strictures
Masses such as cancer in abdo
ENlarged prostate / prostate cancer

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13
Q

What investigation should be done if you cannot find the source of the post renal AKI?

A

USS of the urinary tract to source the blockage

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14
Q

What are some complications of an AKI?

A

Hyperkalemia
Fluid overload - from management
Metabolic Acidosis
Uraemia –> leading to encephalopathy and / or pericarditis

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15
Q

If protein and blood are found in the urinalysis what could be the cause of the AKI?

A

Acute nephritis

or infection

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16
Q

Give some examples of illnesses which can lead to/ make you more vulnerable to, acute tubular necrosis?

A
Cholestatic jaundice
DIC
Liver failure
Pregnancy
Pancreatitis
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17
Q

What are some acute features of acute tubular necrosis?

A
uraemia symptoms:
Anorexia
Vomiting
Pruritis
Drowsiness
Fits
Nausea
Epistaxis
18
Q

Define Acute tubular necrosis:

A

Damage and death of the epithelial cells of the renal tubules.

19
Q

Acute tubular necrosis is reversible - true or false?

A

True

The epithelial cells have the ability to regenerate

20
Q

How long does it usually take to recover from AKI with acute tubular encroiss?

A

7 - 21 days

21
Q

Rhabdomyolysis is a form of ____ AKI?

A

Renal

22
Q

List some toxins which can cause acute tubular necrosis:

A
Gentamicin
NSAIDs
Lithium
Heroin
Radiology contrast dye
23
Q

What is a pathognomonic finding on urinalysis, specific to acute tubular necrosis?

A

Muddy brown casts

Renal tubular epithelial cells in the urine

24
Q

In Acute Tubular necrosis, what 3 things will be raised on biochemistry?

A

Urea
Potassium
Phosphate

25
Q

In acute tubular necrosis, what 3 things will be low on biochemistry?

A

pH
Calcium
Sodium

26
Q

In acute tubular necrosis what part of the kidney specifically is blood flow reduced?

A

Renal cortex

27
Q

What is the main symptom of an AKI resulting from acute tubular necrosis?

A

Oliguria (reduced urine output)

28
Q

Acute tubular necrosis resolves spontaneously. True or false?

A

True

The main aims of management is preventing uraemia hyperkalaemia etc and reducing sepsis risks.

29
Q

What is a severe outcome of acute tubular necrosis if it does not resolve quickly?

A

Cortical necrosis

Caused by reduced blood flow to the renal cortex, and instead of regenerating it heals via scarring (glomerulosclerosis) and eventually necrosis.

30
Q

In an AKI what would be indicators for management with dialysis?

A

Pulmonary oedema
Persistent hyperkalemia despite intervention
Severe metabolic acidosis
Uraemic pericarditis / encephalopathy etc
Drug overdose (to remove drug)

31
Q

List some medications which must be stopped in an AKI as they may worsen the renal funciton?

A
NSAIDs
ACE inhibitors
ARBs
Aminoglycosides
Diuretics
32
Q

In hyperkalemia, which drug is given for cardiac stabilization purposes?

A

Calcium gluconate IV

33
Q

How does insulin and dextrose infusion, and sometimes nebulised salbutamol, help in the management of hyperkalemia?

A

It temporarily reduces the k+ by shifting it from the extracellular to the intracellular compartments.

34
Q

What medications can be given in hyperkalemia to reduce the potassium levels by removing them from the body?

A

Calcium resonium (orally or enema)
(Loop diuretics - use with caution)
Dialysis

35
Q

Give some examples of medications which are suitable to continue in an AKI?

A
Warfarin
Aspirin (at a cardioprotective dose)
Paracetamol
Statins
Clopidogrel
36
Q

Give some examples of medications that are nephrotoxic but do not worsen AKI so can be stopped or continued during an AKI?

A

Lithium
Digoxin
Metformin

37
Q

What would brown granular casts in the urine be suggestive of?

A

renal AKI from Acute tubular necrosis

38
Q

How can you differentiate between a pre renal and renal cause of an AKI?

A

Fluid challenge

If they respond well the cause is probably pre renal

39
Q

In acute tubular necrosis, the serum urea:creatinine ratio will be normal. True or false?

A

True

In pre renal causes the ratio will be higher

40
Q

In a Renal AKI, will the urine osmolality be high or low?

A

Low

roughly <350 mOsm/kg

41
Q

In acute tubular necrosis the urine concentration of sodium will be low. True or false?

A

False

high excretion of sodium is suggestive of an impaired exchange at the tubule which indicates acute tubular necrosis