AKI

Question 1

What is AKI?

Answer 1

Acute kidney injury

Clinical syndrome with abrupt drop in GFR

Question 2

How can AKI be defined?

Answer 2

Increase in serum creatinine by >/= 26.5 umol/L in 48hr

Increase in serum creatinine by >/= 1.5 times baseline in 7 days

Urine volume <0.5ml/kg/h for 6 hours

Question 3

How can AKI be staged?

Answer 3

Stage 1

• increase creatine 150-200%
• urine <0.5ml/kg/hr for 6 hours

Stage 2

• increase creatinine 200-300%
• urine <0.5ml/kg/hr for 12 hours

Stage 3

• increase creatinine >300%
• urine <0.3ml/kg/hr for 24 hours

Question 4

What are the broad categories of AKI causes?

Answer 4

Pre-renal
Renal
Post-renal

Question 5

What causes a pre-renal AKI?

Answer 5

Reduced blood flow to kidneys

Question 6

What is the pathophysiology of a pre-renal AKI?

Answer 6

Reduced GFR due to reduced blood flow

Question 7

What is the renal auto regulation when there is low perfusion?

Answer 7

Increase intrarenal prostacyclins - vasodilate afferent arteriole

Constrict efferent arteriole - angiotensin 2

Question 8

How do ACEi affect renal perfusion?

Answer 8

Reduce amount of angiotensin 2 so less constriction of efferent arteriole

Question 9

How do NSAIDs affect renal perfusion?

Answer 9

Inhibit prostacyclins

Less vasodilation of afferent arteriole

Question 10

What can cause a pre-renal AKI?

Answer 10

Hypovolaemia 
Heart failure 
Sepsis 
Cirrhosis 
Anaphylaxis

Question 11

What can cause a renal AKI?

Answer 11

Acute tubular necrosis
Rhabdomyolysis
Acute interstitial nephritis

Question 12

What is acute tubular necrosis?

Answer 12

Cell damage to tubular cells so that they cannot reabsorbe salt and water efficiently

Question 13

What can cause acute tubular necrosis?

Answer 13

Ischaemia
Sepsis

Nephrotoxins

• drugs (NSAIDs, gentamicin)
• urate
• bilirubin
• myoglobin

Question 14

What is rhabdomyolysis?

Answer 14

Release of myoglobin due to muscle necrosis

Question 15

How does rhabdomyolysis cause an AKI?

Answer 15

Myoglobin is toxic to tubule ells

Question 16

What is a sign of rhabdomyolysis?

Answer 16

Dark ‘coca-cola’ urine

Question 17

What is acute interstitial nephritis?

Answer 17

Inflammation of tubule cells

Question 18

What can cause acute interstitial nephritis?

Answer 18

Toxin induced

• antibiotics
• NSAIDs
• PPIs

Infections

Question 19

What is the pathophysiology of a post renal AKI?

Answer 19

Obstruction

Rise in intraluminal pressure

Dilatation of renal pelvis

Decrease in renal function

Question 20

What is hydronephrosis?

Answer 20

Swelling of renal pelvis due to increased fluid

Question 21

How is an AKI investigated?

Answer 21

Urine dip

USS

Question 22

How do you manage fluid overload in an AKI?

Answer 22

Restrict fluid

Restrict dietary Na

Question 23

How do you manage hyperkalaemia in an AKI?

Answer 23

Calcium gluconate

Restrict dietary K
Stop K-sparing diuretics

Question 24

What are indications for dialysis?

Answer 24

High potassium after treatment 
Metabolic acidosis 
Fluid overload after diuretics 
Signs of uraemia 
Presence of dialyzable nephrotoxin

Question 25

What are signs of uraemia?

Answer 25

Pericarditis
Reduced consciousness
Intractable N+V