Acute Kidney Injury (AKI)

Question 1

Acute kidney disease is an abrupt decline in _____ f_____ (hours to days) characterised by increased serum ______ and ____ and decreased/increased urine output

Answer 1

kidney function
creatinine and urea
decreased urine output

Question 2

In general terms, what causes the decline in kidney function?

Answer 2

Accumulation of usually excreted substances

Question 3

In AKI, the serum creatinine increases by ___ umol/l within 48 hours

Answer 3

26 umol/litre

Question 4

Another way (other than a 26 umol/l creatinine) to define AKI is if the creatinine levels have…

Answer 4

increased by 1.5 times from is baseline within a week

Question 5

How can you define AKI based on urine output?

Answer 5

If urine output < 0.5 ml/kg/hour for at least 6 consecutive hours

Question 6

What classification scale is used to score severity of AKI?

Answer 6

KDIGO (kidney Disease: Improving Global Outcomes)
3 stages

Question 7

Which stage indicates most severe AKI?

Answer 7

Stage 3
3x increase in serum creatinine from baseline
lower likelihood of kidney recovery

Question 8

Causes of AKI are p___, r___ or p_____

Answer 8

prerenal, renal or postrenal

Question 9

What are is the common factor in prerenal causes of AKI?

Answer 9

Hypoperfusion (causing ischaemia, damaging the cells so impaired clearance of waste products)

Question 10

What are some prerenal causes of AKI?

Answer 10

Decreased cardiac output, cardio shock, cardiorenal syndrome

Hypovolaemia secondary to D&V

Liver failure

Renal artery blockage or stenosis

Drugs (NSAIDS and ACE-i which decrease GFR)

IV contrast

Question 11

Name the common factor of renal causes for AKI?

Answer 11

Nephron and parenchyma damage

Question 12

What are some renal causes of AKI?

Answer 12

Glomerulonephritis
Acute tubular necrosis
Acute interstitial nephritis
Rhabdomyolysis (breakdown of striated muscle)
Tumour lysis syndrome

Question 13

What do post-renal problems causing AKI have in common?

Answer 13

Obstruction to urine results in ‘backing-up’ and affecting normal renal function

Question 14

What are some post-renal causes of AKI?

Answer 14

Kidney stone in ureter or bladder
Benign prostatic hyperplasia
External compression of the ureter

Question 15

What are risk factors for AKI?

Answer 15

Chronic kidney disease
Other organ failure eg HF
History of AKI
Nephrotoxic drugs
Iodinated contrast agents
65+ y/o

Question 16

What is oliguria?

Answer 16

urine output of less than 0.5 ml/kg/hour

Question 17

What kinds of drugs have nephrotoxic potential?

Answer 17

NSAIDs
Aminoglycosides (broad-spec antibiotics)
ARBs
Diuretics

Question 18

What are some symptoms of AKI?

Answer 18

Reduced urine output
Pulmonary oedema
Peripheral oedema
Arrhythmias (acid-base balance, potassium levels)
Pericarditis or encephalopathy from uraemia

Question 19

What investigations are there for AKI?

Answer 19

U&E: particularly K+, H+, urea and creatinine

FBC and CRP (c-reactive protein): check for infection

Renal biopsy: confirms intrarenal cause

USS: confirms post renal cuase

Question 20

All patients with suspected AKI should have…

Answer 20

urinalysis

Question 21

How is AKI managed?

Answer 21

Careful fluid balance (diuretics for fluid overload)

Review medications

Treat met acidosis with sodium bicarbonate

Treatment for hyperkalaemia

Last resort = renal replacement therapy (eg haemodialysis)

Question 22

What is treatment option for hyperkalaemia to stabilise the cardiac membrane?

Answer 22

IV calcium gluconate

Question 23

What is a treatment option for hyperkalaemia by shifting potassium from extracellular to intracellular fluid compartment?

Answer 23

Insulin and dextrose infusion

or Nebulised salbutamol

Question 24

Why treatment option for hyperkalaemia aids removal of potassium from the body?

Answer 24

Calcium resonium
or loop diuretics
or dialysis.

Question 25

How can the ratio of urea:creatinine be used to tell whether the cause of the AKI is pre-renal, renal or postrenal?

Answer 25

U: Cr

> 100:1 = prerenal

<40:1 = renal

40-100:1 = postrenal

Question 26

When is Haemodialysis used?

Answer 26

AFUK

Acidosis (pH is lower than 7.1)

Fluid overload (oedema)

Uraemia (symptomatic)

K+ >6.5 (or see hyperkalaemia changes to ECG)

Question 27

What are the ECG changes in hyperkalaemia?

Answer 27

Flattened P wave
Wide QRS
Tall T wave

Question 28

True or false: Ace-i causes dilation of the afferent arteriole?

Answer 28

False
ACE-inhibitors cause constriction of the afferent arteriole so decreases perfusion to the glomerulus

Question 29

What are the top 3 causes of AKI?

Answer 29

Sepsis
Cardiogenic shock
Major surgery

Question 30

What is a characteristic of acute tubular necrosis?

Answer 30

Muddy brown casts in urine (dead tubular cells)