Renal 2) AKI

Question 1

What is an acute kidney injury?

Answer 1

Rapid fall in glomerular filtration rate which impedes kidney’s normal functions within hours to days

Question 2

What is an AKI stage 1?

Answer 2

Increase in serum creatinine of ≥26 micromols/L within 48h or 1.5-2 fold increase from baseline
Urine output <0.5ml/kg/h for >6h

Question 3

What is an AKI stage 2?

Answer 3

Increase in serum creatinine to >2-3 fold from baseline

Urine output <0.5ml/kg/h for >12h

Question 4

What is an AKI stage 3?

Answer 4

Increase in serum creatinine to >3 fold from baseline or serum creatinine >354micromol/l with an acute increase of ≥44micrmol/L
Urine output <0.3ml/kg/h for 24h or anuria for 12h

Question 5

What is creatinine?

Answer 5

Normal product of muscle turnover

Transported by blood and excreted by kidneys

Question 6

Why is creatinine not reliable?

Answer 6

Muscle increases creatinine

Decreased creatinine levels in pregnancy due to increased fluid

Question 7

What is the normal creatinine range in Brighton?

Answer 7

60-100 micromols/L

Individual to each patient

Question 8

What is oliguria?

Answer 8

<0.5mlg/kg/h urine output

Usually <500ml/24h in adults

Question 9

What is anuria?

Answer 9

No urine output

<100ml /24h

Question 10

What are the 4 phases of an AKI?

Answer 10

Onset phase
Oliguric / anuric phase
Polyuric / diuretic phase
Recovery phase

Question 11

What is the onset phase?

Answer 11

Renal blood flow 25% of normal
Tissue oxygenation 25% of normal
Urine output <0.5ml/kg/h

Question 12

What are some common triggering events for an AKI?

Answer 12

Significant blood loss
Fluid loss
Diabetes insipidus

Question 13

What is the oliguric / anuric phase?

Answer 13

Urine output <400ml/day
Increases in blood urea nitrogen and creatinine levels
Electrolyte disturbances, acidosis and fluid overload

Question 14

What is the polyuric / diuretic phase?

Answer 14

Occurs when cause of AKI is corrected
Renal tubule scarring and oedema
Increased glomerular filtration rate
Daily urine output >400ml
Possible electrolyte depletion from excretion of more water and osmotic effects of high blood urea nitrogen

Question 15

What is the recovery phase?

Answer 15

Decreased oedema
Normalisation of fluid and electrolyte balance
Return of GFR to 70-80% of normal

Question 16

What are the functions of the kidneys?

Answer 16

Excretion of toxins e.g. urea
Electrolyte balance 
Acid-base balance
Fluid balance
BP control
Control of bone metabolism, vitamin D activation, phosphate excretion
Production of erythropoietin

Question 17

What are the symptoms of fluid overload?

Answer 17

Breathlessness
Orthopnoea
Limb swelling

Question 18

What are the 4 main indications for dialysis in AKI?

Answer 18

Refractory hyperkalaemia
Pulmonary oedema
Refractory acid/base disturbance
Uraemic complications

Question 19

What are some pre-renal causes of AKI?

Answer 19

Decrease in perfusion pressure resulting in ischaemia or infarction

Bleeding
Septic shock
Dehydration
MI
Iatrogenic
Renal artery stenosis

Question 20

What are some renal causes of AKI?

Answer 20

Direct toxic effects
 - drugs 
 - calcium
Overproduction leading to blockage of tubules
 - rhabdomyolysis
 - myeloma
Inflammation in kidney
 - glomerulonephritis
 - interstitial nephritis
 - Acute tubular necrosis

Question 21

What are some post-renal causes of AKI

Answer 21

Stones
Ureteric / urethral strictures
BPH
Prostate cancer
Urinary retention

Question 22

What are some chronic background risks for AKI?

Answer 22

Elderly
CKD
Cardiac failure
Liver disease
Diabetes
Vascular disease
Background nephrotoxic medications

Question 23

What are some acute risk factors for AKI?

Answer 23

Sepsis and hypoperfusion
Toxins
Obstruction
Parenchyma

Question 24

What are some red flags in the history for AKI?

Answer 24

Haemoptysis
Rashes
Joint pain / swelling
ENT 
Significant acute limb swelling
Urine frothiness
Jaundice

Question 25

What drugs should be stopped in AKI?

Answer 25

ACE inhibitors
Angiotensin receptor blockers
NSAIDs
Any diuretics
Metformin

Question 26

What are the causes of polyuria?

Answer 26

Known and common phase of AKI
Post-relief obstruction
Diabetes mellitus
Psychogenic
Beer potomania
Endocrine causes e.g. diabetes insipidus

Question 27

How should polyuria be managed?

Answer 27

Encourage patient to drink

Provide IV fluids to match output if dry