Acute Kidney Injury

Question 1

What happens to GFR in AKI

Answer 1

It declines rapidly - over hours/days or weeks

Question 2

What can AKI lead on to

Answer 2

CKD

increases your risk

Question 3

What is the definition of AKI

Answer 3

An abrupt (<48hrs) reduction in kidney function : 
Shown by increase in serum creatinine or reduction in urine output

Question 4

List some risk factors for AKI

Answer 4

Older Age
CKD
Diabetes
Cardiac Failure
Liver Disease
Peripheral vascular disease 
Previous AKI
Hypotension
Hypovolaemia 
Sepsis

Question 5

Which medications can cause AKI

Answer 5

Gentamicin, penicillins, trimethaprin

Question 6

List pre-renal causes of AKI

Answer 6

Problems with blood entering kidney:
Hypovolaemia - haemorrhage or volume depletion
Hypotension - shock
Renal hypoperfusion - NSAIDs, ACEi etc

Question 7

How do the kidneys normally react to volume depletion

Answer 7

There is efferent arteriolar vasoconstriction in an attempt to maintain perfusion

Question 8

Why are the kidneys so sensitive to hypovolaemia and hypotension

Answer 8

They need to receive 20% of the cardiac output

Question 9

What does untreated pre-renal AKI lead to

Answer 9

Acute tubular necrosis

Question 10

What can cause acute tubular necrosis

Answer 10

AKI - decreased perfusion
Sepsis and sevre dehydration are most common causes
Rhabdomyolysis
Drug toxicity

Question 11

How do you assess hydration in pre-renal AKI

Answer 11

BP, HR, JVP, cap refill
Look for oedema
urine colour, urine output
Assess skin turgor and mucous membranes

Question 12

How do you treat pre-renal AKI

Answer 12

Fluid challenge
Use crystalloid or colloid
Give in 250ml bolus then reassess and repeat if needed

Question 13

List causes of renal AKI

Answer 13

Vascular - vasculitis
Glomerulonephritis
Interstitial nephritis - drugs, infection or sarcoid
Tubular injury - ischamia, drugs etc

Question 14

List symptoms of renal AKI

Answer 14

Anorexia and weight loss 
Fatigue and lethargy 
Nausea and vomiting 
Itch 
Fluid overload - oedema and SOB
Oliguria

Question 15

What can uraemia cause

Answer 15

Itch

Pericarditis

Question 16

How can compartment syndrome lead to AKI

Answer 16

Leads on to rhabdomyolysis which then leads to AKI

Question 17

How would you investigate renal AKI

Answer 17

U&E
FBC and coagulation screen 
Urinalysis  blood and protein
USS - if obstruction suspected 
Immunology - ANA, ANCA

Question 18

How would you treat renal AKI

Answer 18

Fluid resuscitation 
Give antibiotics if septic 
Treat underlying cause 
Stop any nephrotoxic drugs 
May need dialysis

Question 19

When might someone with AKI be put on dialysis

Answer 19

If not passing any urine may require urgent dialysis
Hyperkalaemia
Severe acidosis
Fluid overload

Question 20

List complications of AKI

Answer 20

Hyperkalaemia 
Fluid overload - pulmonary oedema 
Severe acidosis 
Uremic pericardial effusion
Severe uraemia

Question 21

What can cause post-renal AKI

Answer 21

Obstruction of urine flow leading to back pressure:

Stones, cancer, strictures, extrinsic pressure

Question 22

How does urine obstruction appear on USS

Answer 22

Dilated renal pelvis (indicates hydronephrosis due to a blockage)

Question 23

How do you treat post-renal AKI

Answer 23

Relive the obstruction by catheter or nephrostomy

Question 24

What is the definition of hyperkalaemia

Answer 24

> 5.5

becomes life threatening at >6.5

Question 25

What is the major consequence of hyperkalaemia

Answer 25

Cardiac arrhythmia

Need to do an ECG

Question 26

How do you treat hyperkaaemia

Answer 26

Cardiac monitor
Give 10mls 10% calcium gluconate to protect myocardium
Give Actrapid insulin with dextrose - move K back into cells
Salbutamol nebulised for 90mins
Calcium resonium if in community