10a.) AKI Flashcards
What % of cardiac output do the kidneys receive?
25%
AKI is about as common as acute myocardial infarction; true or false
True
Compare the mortality of AKI to mortality of MI
- MI: 5-10%
- AKI: 25-30%
Length of stay for AKI much longer. Just know idea that AKI is SERIOUS
Define AKI
AKI (acute kidney injury) is a decline in GFR that occurs during a short period of time (e.g. over max of 7 days)
How do we measure a decline in GFR in AKI?
High serum creatinine= low GFR
NICE guidelines state that you can detect AKI using numerous critera; state the 4 possible criteria you can use to detect AKI
- A rise in serum creatinine of 26umol/L or greater within 48 hours
- A 50% or greater rise in serum creatinine known or presumed to have occurred in past 7 days
- A fall in urine output to less than 0.5ml/kg/hour for more than 6 hours in adults and more than 8 hours in children and young people
- A 25% or greater fall in eGFR in children and young people within past 7 days
Describe the KDIGO criteria for AKI staging
Focus on the multiplication (x1.5, x2 etc…)
AKI can be oliguric or non-oliguric; state what each means
- Oliguric: less than 500ml of urine per day/less than 20ml per hour
- Non-oliguric: opposite to above/not the above
Define anuria
No urine; defined as less than 100ml of urine per day
What does anuria often indicate?
Is it a common form of AKI?
- Anuria often indicates a blockage of urine flow or very severe kidney damage
- Not common form of AKI
Oliguria is defined as less than 500mls of urine per day; where does the value of 500mls come from?
- For an average sized individual, about 600mOsm/day of cellular waste products need to be excreted
- Maximal concentrating ability of kidneys is 1200mOsm/L hence minimal volume of urine to excrete cellular waste each day is 500ml
Which of the following is the least common cause of AKI:
- Dehydration
- Sepsis
- Glomerular disease
- Obstructive nephropathy
- Drug induced nephropathy
- Glomerular disease
We can classify the causes of AKI into 3 distinct categories; state and describe these categories and provide examples for each
-
Pre-renal: inadequete perfusion to kidneys which could be due to:
- Reduced cardiac function
- Volume depletion e.g. hypovolaemic shock
- Obstruction of arterial supply to kidneys
- Medications
-
Intrarenal/renal: direct damage to kidneys which could be due to:
- Inflammation
- Toxins
- Drugs
- Infection
- Glomerular disease
- Sepsis
- Rhabdomyolysis
-
Post-renal: obstructin to urinary flow which causes back pressure and inhibits filtration. Subsequetn swelling can also compress blood vessels can cause ischaemia. ExampleS:
- Enlarged prostrate
- Kidney stones
- Tumour
Is pre-renal AKI reversible if caught and treated promptly?
Yes, because kidney injury has not yet occured decreased GFR is due to decreased renal perfusion
If pre-renal AKI is not identified and treated promptly is it still reversible?
Might become irreversible as kidney cells are starved of oxygen (those with highest metabolic requireents e.g. proximal tubules) are more at risk. If pre-renal AKI sustained for long enough it can lead to ATI (acute tubular injury)
Explain what rhabdomyolysis is
Explain how it can cause AKI
Explain the appearance of urine of someone with rhabodmyolysis
- Rapid breakdwon of skeletal muscle causing release of myoglobin into blood which is harmful to kidneys and can thefore lead to AKI (renal cause)
- Cola-coloured urine due myoglobin in urine
Treatment of AKI depends on cause of AKI; true or false?
True
Describe how might treat pre-renal causes of AKI
- Restore volume e.g. fluids
- Terat pump failure
How would you manage AKI due to ATI (acute tubulary injury)?
- Recovery can take several weeks adn treatment is supportive
- Maintain good kidney perfusion
- Avoid nephrotoxins (e.g. radio-contrast dye)
- Restrict various solutes (e.g. potassium)
- Provide nutritional support
Why should you do a urine dipstick for all patients with AKI?
To rule out intrinsic causes of AKI as these need different management e.g. immunosuppression.
For example:
- Leukocytes & nitrates- infection
- Blood- renal or post-renal disease
State some aspects of presentation e.g. history, symptoms and investigation results that would suggest rhabdomyolysis as a cause of AKI
- History of trauma e.g. fall in elderly
- Muscle pain
- Increased creatine kinase, myoglobinuria
Why must you monitor electrolytes carefully in patient with AKI?
- Electrolyte disturbances e.g. hyperkalaemia can cause massive cardiac arrest
- Uraemia
State some symptoms of AKI
- nausea or vomitting
- diarrhoea
- dehydration
- peeing less than usual
- confusion
- drowsiness
What is most common cause of AKI out of:
- Pre-renal
- Renal
- Post-renal
- Pre-renal
- Out of all pre-renal causes ATI is most common (cells in tubules get damaged and stop working)
