acute kidney injury

Question 1

what is the definition of acute kidney injury?

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

Question 2

what are some risk factors for AKI?

Answer 2

• Older Age
• CKD
• Diabetes
• Cardiac Failure * Liver Disease
• PVD
• Previous AKI
• Hypotension
• Hypovoleamia
• Sepsis
• Deteriorating NEWS
• Recent Contrast
• Exposure to Certain Medications

Question 3

what are some pre renal causes of AKI?

Answer 3

• hypovolaemia- haemorrhage, D&V, burns
• hypotension- cardiogenic shock, sepsis, anaphylaxis
• renal hypoperfusion - NSAIDs/ COX-2, ACEis / ARBs, hepatorenal syndrome

Question 4

what are the signs of pre-renal AKI?

Answer 4

reversible volume depletion leading to oliguria (<0.5ml/kg/hr) and increased creatinine

Question 5

what is the commonest form of AKI in hospital?

Answer 5

acute tubular necrosis - commonly caused by sepsis and severe dehydration

Question 6

what is the treatment of pre-renal AKI?

Answer 6

assess for hydration- clinical obs, JVP, cap refill, pulmonary oedema
- fluid challenge for hypovolaemia - crystalloid (0.9% NaCl) or colloid (gelofusion) NOT dextrose
give bolus then reassess
if >1L necessary with no improvement seek help

Question 7

what are vascular causes of renal AKI?

Answer 7

vasculitis or renovascular disease

Question 8

what is the cause of glomerular renal AKI?

Answer 8

glomerulonephritis

Question 9

what are causes of interstitial renal AKI?

Answer 9

drugs (e.g. antibiotics, ppis, NSAIDs), infection (TB), systemic (sarcoid)

Question 10

what are causes of tubular injury leading to renal AKI?

Answer 10

ischaemia, drugs (gentamicin), contrast, rhabdomyolysis

Question 11

what are the signs and symptoms of AKI?

Answer 11

non-specific symptoms- anorexia, weight loss, fatigue, nausea and vomiting, itch, oedema and SOB, uraemia, pericarditis, oliguria

Question 12

what are clues to renal cause of AKI?

Answer 12

sore throat (strep), rash, joint pains, D&V, haemoptysis, eosinophilia (interstitial nephritis), CK (rhabdomyolysis), vascular bruits

Question 13

what are the initial investigations in AKI?

Answer 13

U&Es, FBC and coagulation screen, urinalysis, USS, immunology, protein electrophoresis

Question 14

what causes 1 big and 1 small kidney?

Answer 14

renal artery stenosis

Question 15

what are the life threatening complications of AKI?

Answer 15

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

Question 16

what are the levels of hyperkalaemia from normal to life threatening?

Answer 16

• Normal K = 3.5-5.0
• Hyperkalaemia = >5.5
• Life threatening hyperkalaemia = >6.5

Question 17

how do you assess hyperkalemia?

Answer 17

ECG- peaked T waves, no P waves

Question 18

what is the treatment of hyperkalaemia?

Answer 18

Cardiac Monitor & IV access Protect myocardium
– 10mls 10% calcium gluconate (2-3mins) Move K+ back into the cells
– Insulin (actrapid 10units) with 50mls 50% dextrose (30 mins)
– Salbutamol Nebs (90 mins)
Prevent absorption from GI tract
– Calcium resonium (NOT in the acute setting)

Question 19

what are urgent indications for haemodialysis?

Answer 19

• hyperkalaemia >7 or >6.5 & unresponsive to medical therapy
• severe acidosis (pH < 7.15)
• fluid overload
• urea > 40, pericardial rub / effusion

Question 20

what are risk factors for contrast induced nephropathy?

Answer 20

renal impairment - +/- diabetes mellitus
dehydration
congestive heart failure
LV ejection fraction < 40%
acute MI (within 24 hours)
nephrotoxic drugs

Question 21

what is the management of contrast induced nephropathy?

Answer 21

Give either Sodium Chloride or Sodium Bicarbonate as follows:
IV 0.9% Sodium Chloride
1000ml at 83ml/hour 12 hours before and 12 hours after the scan
IV 1.26% Sodium Bicarbonate
500ml at 71ml/hour Starting 1 hour before and continuing for 6 hours after