acute kidney injury

Question 1

what is the definition of AKI?

Answer 1

An abrupt (<48hrs) reduction in kidney
function defined as
– an absolute increase in serum creatinine by
>26.4µmol/l
– OR increase in creatinine by >50%
– OR a reduction in UO

this definition can only be applied following adequate fluid resuscitation and exclusion of obstruction

Question 2

what are the risk factors for an AKI?

Answer 2

Older Age
CKD
Diabetes
Cardiac Failure
Liver Disease
PVD
Previous AKI
Hypotension
Hypovoleamia
Sepsis

Question 3

what are some pre renal causes of AKI?

Answer 3

hypovolaemia- haemorrhage, volume depletion
hypotension- cardiogenic shock, distributive shock (eg sepsis)
renal hypoperfusion- NSAIDs, ACEi/ARB

Question 4

what is pre renal AKI?

Answer 4

reversible volume depletion leading to oligouria (<0.5mls/kg/hr) and an increase in creatinine

Question 5

what can untreated pre renal AKI lead to?

Answer 5

acute tubular necrosis

Question 6

what is acute tubular necrosis?

Answer 6

common form of AKI in hospital
decreased renal perfusion
commonly caused by severe dehydration and sepsis. can also be caused by rhabdomyolysis and drug toxicity

Question 7

what is the treatment for pre renal AKI?

Answer 7

assess for hydration (done clinically)
fluid challenge for hypovolaemia
- crystalloid (0.9 NaCl)
- DO NOT give 5% dextrose
- if >1000mls given and no improvement seek help

Question 8

what is renal AKI?

Answer 8

inflammation or damage to cells causing AKI

Question 9

what are causes of renal AKI?

Answer 9

vascular- vasculitis, renovascular disease
glomerular- glomerulonephritis
interstitial nephritis- drugs (abx, PPI), infection (TB), systemic (sarcoidosis)
tubular injury- ischaemia, drugs (gentamicin), contrast, rhabdomyolysis

Question 10

what are the signs and symptoms of an AKI?

Answer 10

non specific symptoms eg weight loss, fatigue, nausea, itch
fluid overload eg oedema
uraemia, including itch and pericarditis
oligouria

Question 11

what are the initial investigations for renal AKI?

Answer 11

U+E (check potassium)
FBC and coag screen (abnormal clotting and anaemia)
urinalysis (haematoproteinuria)
USS (obstruction?)
immunology (ANA, ANCA, GBM)

Question 12

how is AKI treated?

Answer 12

good perfusion pressure
treat underlying cause
stop nephrotoxics
dialysis if remains anuric and uraemia

Question 13

what are the life threatening complications of AKI?

Answer 13

hyperkalaemia
fluid overload (pulmonary oedema)
severe acidosis (pH<7.15)
uraemic pericardial effusion
severe uraemia (Ur>40)

Question 14

what does 1 normal and 1 small kidney indicate?

Answer 14

renal artery stenosis

Question 15

what is a post renal AKI?

Answer 15

AKI due to obstruction of urine flow leading to back pressure (hydronephrosis) and thus loss of concentrating ability

Question 16

what are the causes of a post renal AKI?

Answer 16

stones, cancers, strictures, extrinsic pressure

Question 17

how is a post renal AKI treated?

Answer 17

relieve obstruction
-catheter
- nephrostomy
refer to urology if ureteric stenting required

Question 18

what is the range for hyperkalaemia?

Answer 18

> 5.5
life threatening >6.5

Question 19

what are the ECG changes in hyperkalaemia?

Answer 19

peaked T waves
flattened P waves
prolonged PR intervals and QRS duration

Question 20

what does calcium gluconate do in hyperkalaemia?

Answer 20

stabelise the cardiac membrane

Question 21

how is life threatening hyperkalaemia treated?

Answer 21

protect myocardium with 10mls 10% calcium gluconate (2-3mins)
Move K back into cells- insulin, with 50% dextrose and a salbutamol neb

Question 22

what are the indications for dialysis

Answer 22

Hyperkalaemia
– >7
– >6.5 unresponsive to medical therapy
Severe Acidosis
– pH < 7.15
Fluid overload
Urea >40, pericardial rub/effusion