2.06 - Acute Kidney Injury: Causes & Epidemiology

Question 1

What is the definition of AKI?

Answer 1

A rapid decline in glomerular filtration rate, resulting in disturbance of renal physiological functions. Clinically manifest as an abrupt and sustained rise in urea and creatinine

Question 2

What are the three causes of AKI?

Answer 2

Pre renal disease (40-70%)
Intrarenal/Intrinsic Renal (10-50%)
Post-renal or obstructive (10%)

Question 3

Describe Pre-Renal AKI

Answer 3

The reduction in GFR is caused by abnormalities in glomerular perfusion. Resolves rapidly when the underlying cause oh hypo perfusion is corrected

Question 4

What are some causes of Pre-Renal AKI?

Answer 4

Hypovolaemia (vomiting, diarrhoea, diuretics)
Renal hypoperfusion (NSAIDs & ACEI, renal artery stenosis, hepatorenal syndrome)
Hypotension (cardiogenic, septic)
Oedematous states (nephrotic syndrome, cardiac failure –> reduces effective blood volume)

Question 5

What are some causes of Intrinsic Renal Failure?

Answer 5

Glomerulonephritis
Acute tubular necrosis (Toxins, Drugs)
Acute interstitial nephritis
Small vessel disease

Question 6

What are some post-renal causes of AKI

Answer 6

Intrinsic: stones, blood clots, prostate enlargement, bladder cancer.
Extrinsic: pelvic malignancy, retroperitoneal fibrosis

Question 7

What type of AKI is this?
35 yo male
Holidays in asia
Vomiting and diarrhoea
↓ urine output
BP 70/50mmHg (low)
Pulse 120/min (high)
Blood tests:
o Urea: 40
o Creatinine: 256
o K+ = 4.5
o HCO3 = 15 (low; acidosis)
Urine Na+: 12 (low)

Answer 7

Pre-renal failure as low volume (vomiting and diarrhoea) and a low BP

Question 8

What type of AKI is this?
55 yo female
tiredness,oedema
urine: – blood cells, protein ++
Blood:
o Urea: 20 (high)
o Creatinine: 246 (high)
BP: 130/80mmHg (normal)

Answer 8

intrinsic: blood in the urine indicate the problem is in the filters

Question 9

What is the RIFLE criteria for AKI

Answer 9

Risk
Injury
Failure
Loss
End-Stage Renal Disease
A criteria for classifying AKI severity. Uses GFR and urine output to categorise patients

Question 10

Describe the KDOQI2012

Answer 10

This criteria considers change in serum creatinine and urine output, but not GFR for staging:
Stage 1: 1.5-1.9 times baseline OR an >26.5 increase in creatinine OR urine output 12 hours

Stage 3: 3.0 times baselines increase in the serum creatinine OR increase in serum creatinine to >353.6 OR urine output of 24 hours, OR anuria for >12 hours OR the initiation of renal replacement therapy

Question 11

What are the three types of AKI based on geographical source?

Answer 11

Community Acquired
Hospital Acquired
ICU Based

Question 12

What are the common causes of community acquired AKI?

Answer 12

Rhabdomyolysis after earthquakes, crush injury
Industrial accidents
South East Asia – diarrhoea and malaria
Nigeria – amanita mushrooms

Question 13

What are the causes of Hospital Acquired AKI

Answer 13

Causes are ischaemic or toxic induced

Ischaemic is pre-renal progressing on to intrinsic. Usually multifactorial

Question 14

What are the risk factors for AKI in hospitalised patients?

Answer 14

Post operative:
Haemodynamic compromise o Infection and sepsis
Cardiac surgery

Contrast nephropathy:
Low blood pressure
Risk due to contrast much high in patients with low BP
Diabetes mellitus o Preexisting renal
impairment
Volume of contrast

Nephrotoxic antbiotics:
Vancomycin

Sepsis

Question 15

Describe the purpose for the development of the RIFLE criteria

Answer 15

Because people use different values for the cut off of creatinine.
Different cases: outpatients have different causes that those in ICU for example
Lack of consensus in the quantitative definition of AKI
Different in general population, hospitalised patients and ICU patients
Differences between developing and developed countries