AKI Management

Question 1

What does AKI management depend on?

Answer 1

Underlying aetiology
Pre-renal - correct volume depletion and restore kidney perfusion with circulatory cardiac support, treat underlying sepsis
Renal - refer for biospy and specialist renal treatment
Post-renal - catheter, nephrostomy or urological intervention

Question 2

How is pre-renal failure treated

Answer 2

Restore renal perfusion by restoring circulatory volume or trading pump failure.
E.g. fluid administration or use of diuretic in heart failure
Treat volume overload
Treat hypovolaemia with fluids
Treat hyperkalaemia by restricting K intake and removing K sparing medicines
Dialysis

Question 3

How is post-renal failure treated

Answer 3

Urological intervention, catheter, nephrostomy (artificaial opening between kidneys and skin allowing passage of urine.

Question 4

Give support for established ATN

Answer 4

Stop nephrotoxic meds - NSAIDs, ACE-i, ATII antag, aminoglycosides
Stop complication drugs - K-sparing diuretics
Nutritional support and gastro protection (PPI,H2antag)

Question 5

What can the volume status be in AKI? What signs are there for each

Answer 5

Hypovolaemia - underperfusion
Hypotension, oliguria,, non-visible JVP, poor tissue turgor, raised pulse, daily weight loss

Hypervolaemia - fluid overload
Hypertension, Raised JVP, lung crepitations, peripheral oedema, gallop rhythm

Question 6

How is hypovolaemia treated?

Answer 6

Dynamic assessment - examine before and after all fluid given to ensure adequate response and to avoid fluid overload.
Take care in cardiac disease (reduced renal perfusion despite adequate volume) and sepsis (increased extravascular volume)

Give 500ml crystalloid over 15 mins
Reassess fluid state - get help is still shocked
Further boluses of 250-500ml crystalloid with review after each
Stop when euvolaemic or 2L given

Question 7

Which crystalloid should be given to treat hypovolaemia?

Answer 7

Any can be used:
0.9% saline - contains chloride and is not buffered, may cause hyperchloraemic acidosis (review anion gap)
Balanced/buffered crystalloid - Hartman’s Ringers lactate - contain 4-5mM/L of K so caution if hyperkalaemia and oliguria

Question 8

When should colloid be given?

Answer 8

Blood components if hypovolaemia due to haemorrhage.

Question 9

Why does hypervolaemia occur?

Answer 9

Aggressive fluid resuscitation, oliguria, and in sepsis due to increased capillary permeability.

Question 10

How is hypervolaemia treated?

Answer 10

Oxygen if required
Fluid restriction
Antibiotics in minimal fluid and concentrated nutritional support prepartaions
Diuretics - only if symptomatic
RRT - AKI with fluid overload and oligo/anria

Question 11

When to treat hyperkalaemia?

Answer 11

K > 6,5mM/L

or ECG changes

Question 12

How is hyperkalaemia treated?

Answer 12

1 10 ml of calcium chloride IV via a big vein over 5-10mins, repeated if necessary if ECG changes persist. Cardioprotective but does not treat hyperkalaemia.
2 IV insulin in 25g glucose. Insulin stimulates intracellular K uptake, lowering serum K. Monitor hourly for hypoglycaemia
3 Salbutamol also causes intracellular K shift but at high doses, avoid in tachycardia
4 K removal for definitive treatment. If underlying pathology cannot be corrected, RRT.

Question 13

What are RRT options in AKI?

Answer 13

Haemodialysis and haemofiltration

Question 14

What are indications for RRT?

Answer 14

Fluid overload unresponsive to treatment
Sever/prolonged acidosis
Recurrent/persistent hyperkalaemia
Uraemia (raised urea in blood) causing pericarditis and encephalopathy