AKI

Question 1

What is AKI?

Answer 1

Acute kidney injury (AKI) is a syndrome of decreased renal function, measured by serum creatinine or urine output, occurring over hours–days. It includes different aetiologies and may be multifactorial.

Question 2

How is AKI stage?

Answer 2

3 stages based on urine output or creatinine

Question 3

What are the different stages?

Answer 3

Stage 1 - Serum Cr 1.5-1.9 x baseline or >26.5umol/L; Urine output <0.5ml/kg/h for 6-12 hours

Stage 2 - Serum Cr 2.0–2.9 x baseline; Urine output <0.5ml/kg/h for >12 hours

Stage 3 - Serum Cr >353.6μmol/L (4.0mg/dL) or >3.0 x baseline or
renal replacement therapy; UO <0.3mL/kg/h for >24h or anuria for >12h

Question 4

What is the framework to manage AKI?

Answer 4

SALFORD

Sepsis and other causes - treat
ACEI/ARB and NSAIDs - suspend/review
Labs and leaflets
Fluid assessment and response
Obstruction - USS within 24 hours in non-resolving AKI 3 of unknown cause
Renal/critical care referral - non-resolving AKI 3, anuric, CKD 4-5, severe complication
Dip urine and document it

Question 5

What is the commonest causes of AKI?

Answer 5

Pre-renal disease or ATN

Question 6

What is the aetiology of AKI?

Answer 6

Pre-renal - decreased perfusion to the kidney
Renal - intrinsic renal disease
Post-renal - obstruction to urine

Question 7

What are pre-renal causes of AKI?

Answer 7

Dehydration, sepsis, hypotension, shock, hepatorenal syndrome, HF

Question 8

What are the renal causes of AKI?

Answer 8

Glomerulonephritis, ATN, vasculitis, contrast, NSAIDs, ACEI, ARBs, gentamicin, interstitial disease

Question 9

What are the post-renal causes of AKI?

Answer 9

prostatic hypertrophy, renal stones, pelvic cancer

Question 10

What should be done on admission to A&E in terms of kidneys?

Answer 10

1) Renal function, blood pressure, temperature and pulse checked
2) risk assessment for the likelihood of developing AKI
3) high serum creatinine, it is important to establish whether this is an acute or acute-on-chronic phenomenon

Question 11

What are life-threatening complications of AKI? (3)

Answer 11

1) Scoring on NEWS - consider critical care referral
2) Pulmonary oedema
3) Hyperkalaemia

Question 12

What do you look for O/E in suspected AKI patients?

Answer 12

HR, BP, JVP, Cap refill, palpate for bladder

Question 13

How do you treat hypovolaemia?

Answer 13

Bolus fluid 250–500mL of crystalloid over less than 15 mins, until volume replete. If 2L given without response, seek expert help.

Question 14

What monitoring do you carry out? (5)

Answer 14

1) Fluid balance - urinary catheter and hourly urine output
2) K+
3) Observations - every 4 hr
4) lactate - if signs of sepsis
5) daily creatinine

Question 15

What investigations do you carry out? (5)

Answer 15

1) Urine dip - haematuria/proteinuria may suggest intrinsic renal disease
2) USS within 24 hours. small kidneys –> CKD.
3) check liver function (hepatorenal)
4) check platelets
5) investigate for intrinsic renal disease: Igs, auto-antibodies

Question 16

How is AKI managed?

Answer 16

Pre-renal: correct volume depletion and/or increase renal perfusion via circulatory/cardiac
support, treat any underlying sepsis.

Renal: refer for likely biopsy and specialist treatment of intrinsic renal disease.

Post-renal: catheter, nephrostomy, or urological intervention

Common to all - manage fluid balance (match to UO + 500mL), acidosis, hyperkalaemia, correct hypovolaemia, stop nephrotoxic drugs, nutritional support, H2-receptor antagonist to stop upper GI bleed, body weight

Question 17

What are the clinical features of pre-renal AKI? (5)

Answer 17

Tachycardia, postural hypotension, poor peripheral pefusion, metabolic acidosis, hyperkalaemia

Question 18

What are the clinical features of GN and acute interstitial nephritis? (2)

Answer 18

Patients with glomerulonephritis usually demonstrate significant haematuria and proteinuria

Acute interstitial nephritis - suspected in a previously well patient if there is an acute deterioration of renal function coinciding with the introduction of a new drug treatment

Question 19

What are the clinical features of post-renal AKI?

Answer 19

bladder enlargement, USS for obstruction, hydronephrosis

Question 20

What is hydronephrosis

Answer 20

Refers to distension and dilation of the renal pelvis and calyces, usually caused by urinary retention due to obstruction of the free flow of urine from the kidney. Untreated, it leads to progressive atrophy of the kidney.

Question 21

What is Acute tubular necrosis?

Answer 21

Kidney damage due to hypoperfusion. Usually the result of a combination of factors which have caused renal ischaemia and toxicity, e.g. hypotension and dehydration or sepsis with associated nephrotoxic drugs.

Question 22

What are the 3 stages of Acute Tubular Necrosis?

Answer 22

Oliguric, maintenance, polyuric

Question 23

A 72-year-old woman who has been on the ward for the past five days is noted by the nurses not to be passing much urine. She was admitted originally with pneumonia but has since developed diarrhoea. Blood tests show her creatinine has increased from 98 to 172 µmol/l. Which tests is most useful when determining whether there is prerenal uraemia or acute tubular necrosis?

Answer 23

Urinary Sodium

Question 24

What are the commonest causes of pre-renal AKI?

Answer 24

true volume depletion due to gastrointestinal (diarrhoea, vomiting), renal (diuretics), or third space fluid and electrolyte losses and haemorrhage.

Question 25

What are risk factors for AKI?

Answer 25

Age, NSAID use, previous AKI, diabetes, HTN

Question 26

Which 3 groups of drugs have NICE said that if started in the last week is recognised as a risk factor for AKI?

Answer 26

ACE-I, ARB and NSAIDs

Question 27

Which patients require discussion with the renal team? (4)

Answer 27

• All patients with a renal transplant
• All patients with an AKI 3
• All AKI (stage 1, 2, or 3) patients with blood & protein on urine dipstick
• All patients who have no known cause of their AKI and have deteriorating renal function.

Question 28

Which complications of AKI require renal replacement therapy? (4)

Answer 28

• uraemic encephalopathy/coma
• Metabolic acidosis that doesn’t respond to medical management
• refractory hyperkalaemia that doesn’t respond to medical management
• severe pulmonary oedema that doesn’t respond to medical management

Question 29

What electrolyte imbalance does omeprazole cause?

Answer 29

Hyponatriemia

Question 30

What would urine osmolality and sodium in pre-renal AKI show?

Answer 30

urine osmolality high, urine sodium low

Question 31

What would urine osmolality and sodium in renal AKI/ATN show?

Answer 31

urine osmolality low, urine sodium high