L09a: Acute Kidney Injury Flashcards
What is acute kidney injury
A rapid (hours to days) decline in kidney function
What do we measure to look at acute kidney injury
Serum creatinine levels
Urine output
Can we use estimated GFR to look at acute kidney injury
No
Why can we not look at estimated GFR
Estimated GFR only works with people stable kidney disease
How many stages of acute kidney injury is there
3
Which stage is the worst acute kidney injury
Stage 3
What happens to creatinine levels as the stages of acute kidney injury increase
Serum Creatinine levels increase
What happens to the urine output as stages of acute kidney injury increase
Urine output decreases
What are the main categories of causes of AKI
Pre-renal
Renal
Post renal
What is pre-renal causes about
Perfusion of the kidney
What is renal causes of about
Kidney disease within the kidney
What is the post renal causes about
Obstruction of the urinary tract
Why can people get perfusion failure due to
Hypotension
Hypovolaemia (low blood volume)
Haemorrhage
Renal artery occlusion
Which drugs make perfusion failure worse
RAAS blockade
NSAIDS
Anti hypertensives
Diuretics
What is renal auto regulation
The maintenance of blood flow despite the changes of blood pressure within a given range
What happens to the blood flow when blood pressure decreases beyond the auto regulation range
Blood flow decreases
Describe the mechanism of the RAAS in low blood pressure/ low blood volume
1) macula densa cells detect low sodium
2) signal is sent to the JGA cells to release renin
3) renin converts angiotensinogen to angiotensin 1
4) ACE converts angiotensin 1 to angiotensin 2
5) angiotensin 2 causes the release of aldosterone form the adrenal cortex
6) aldosterone increases the insertion of sodium eNac channels to increase sodium reabsorption in the collecting duct
7) water follows sodium so blood levels rise
8) angiotensin 2 causes vasoconstriction of blood vessels which also causes a rise in blood pressure
What type of drug can block renin
Renin inhibitors
What type of drug can inhibit the conversion of angiotensin 1 to 2
Ace inhibitors
What type of drug can block the action of angiotensin 2 on the blood vessels
Angiotensin 1 receptor antagonist
What type of drug can block the action of aldosterone
Mineralocorticoid receptor antagonist
Therefore when the patient uses drugs that block the RAS what do they get
Perfusion failure because they cannot rise the pressure and the pressure goes below the autoregulation range
How do we treat perfusion failure
Stop RAS blocking drugs
Give blood / fluid replacement
Blood pressure support
Stop NSAIDs
How can we have obstruction in acute kidney injury
Stones
Tumours
Fibrosis
Benign prostate
What is the treatment of obstruction
Remove or bypass the obstruction
What are the causes of renal disease
Disease that damage the nephron Systemic disease: inflammation Infection Allergic Drug toxicity Glomerulonephritis
What is the treatment for inflammatory renal disease
Steroids
Cyclophosphamide
Plasma exchange
Azathioprine
