7.6 Pathophysiology of AKI

Question 1

What are the three mechanisms of kidney injury?

Answer 1

Pre renal
Intra renal
Post renal

Question 2

What chemicals/ hormones cause afferent pre renal injury?

Answer 2

NO and prostaglandins

Question 3

What chemicals/ hormones cause efferent pre renal injury?

Answer 3

ANG2

Question 4

Describe the mechanisms of tubular injury

Answer 4

Ichaemia-reperfusion
loss of brush border with cell polarity
necrosis and apoptosis
Sloughing of viable and dead cells with luminal obstruction
Dedifferentiation of viable cells
Proliferation
Differentiation and re-establishment of polarity

Question 5

When can more epithelium be made?

Answer 5

When the basement membrane is viable

Question 6

What is the proposed mechanism for contrast induced AKI?

Answer 6

Reduced nephron mass vulnerable to injury
Contrast enters renal vasculature
Adenosine and endothelin release and prostaglandin dysregulation
Sustained intrarenal vasoconstriction
Prolonged contrast transit time and medullar hypoxia
Contrast direct cellular injury and death and ischamic injury and death
AKI

Question 7

Mechanisms of post renal AKI

Answer 7

Back pressure resulting i tubule-glomerular feedback
Upregulation of ANG2 production with downstream impact on pro-fibrotic pathways
Decreased renal blood flow

Question 8

What is the risk category of RIFLE?

Answer 8

> 1.5 baseline or >25% decrease in GFR (cratinine) and 0.5ml/kg/hour urine output in > 6 hours

Question 9

What is the injury category of RIFLE?

Answer 9

> 2 baseline or 50% decrease in GFR and 12 hours

Question 10

What is the failure category of rifle?

Answer 10

> 3 x baseline or >75% decrease in GFR and 24 hours or anuria

Question 11

What is the loss category of RIFLE?

Answer 11

dialysis dependent AKI > 4 weeks

Question 12

What is the end stage category of rifle?

Answer 12

Dialysis dependent > 3 months