AKI

Question 1

Define AKI

Answer 1

abrupt deterioration in renal function, usually over hours or days

Question 2

What is the KDIGO definition of AKI? (3)

Answer 2

• rise in serum creatinine >26μmol/L within 48 hours
• rise in serum creatinine 1.5x baseline within 7 days
• urine output <0.5ml/kg/hr for >6 consecutive hours

Question 3

In terms of serum creatinine and urine output, define the three stages of AKI

Answer 3

1. serum creatinine 1.5-1.9x baseline
   urine output <0.5ml/kg/hr for 6-12 hours
2. serum creatinine 2-2.9x baseline
   <0.5ml/kg/hr for ≥12 hours
3. serum creatinine >3x baseline or ≥345
   urine output <0.3ml/kg/hr for ≥24 hours or anuria for 12 hours

Question 4

Name 4 risk factors for the development of AKI

Answer 4

1. pre-existing CKD
2. increasing age
3. male
4. co-morbidities

Question 5

1. What is true hypovolaemia?

2. What is relative hypovolaemia?

Answer 5

1. reduced circulating blood volume

2. normal/increased circulating volume but kidney’s inadequately perfused

Question 6

Name causes of pre-renal AKI

Answer 6

true hypovolaemia - haemorrhage, burns, D&V, DKA/HSS

relative hypovolaemia - sepsis, hepatorenal syndrome, NSAIDs, ACE/ARB

Question 7

Name causes of renal AKI

Answer 7

glomerular - glomerulonephriyis, acute tubular necrosis

interstitial - drug reaction, infection, infiltration

vessels - vasculitis

Question 8

Name causes of post-renal AKI

Answer 8

stone, malignancy, stricture, clot, prostatic hypertrophy

Question 9

What initial investigations should be done for ?AKI

Answer 9

1. Basic Obs and NEWS2 score
   
   • are there signs of hypovolaemia?
2. VBG to obtain serum K+
3. serum creatinine

Question 10

What needs to be monitored for patients with AKI?

Answer 10

1. catheterise to monitor urine output
2. serum potassium
3. observations every 4 hours
4. lactate
5. daily creatinine

Question 11

What investigations can be useful in determining cause of AKI

Answer 11

1. urine dip - proteinuria and/or haematuria may indicate intrinsic renal disease
2. ultrasound - renal size (can indicate CKD); evaluation of post-obstructive causes
3. LFTs (hepatorenal syndrome)
4. specific tests for intrinsic renal diseases

Question 12

What medical support is given to patients with AKI?

Answer 12

1. stop nephrotoxic medication - NSAIDs, ACE/ARB, aminoglycosides
2. stop drugs that may increase complications - diuretics, metformin
3. check all drug doses and adjust for renal impairment
4. consider gastroprotection and nutritional support
5. avoid radiological contrast

Question 13

1. What is given for cardioprotection in patients with hyperkalaemia?
2. How is hyperkalaemia reduced?

Answer 13

1. IV calcium chloride

2. IV insulin, salbutamol, renal replacement

Question 14

Name causes of acute-on-chronic kidney failure (10)

Answer 14

systemic infection
Drugs - diuretics, ACE inhibitors, aminoglycosides
Dehydration
Urinary tract obstruction/urinary retention
Volume depletion
DKA, HSS
Hypercalcaemia
Hyperuricaemia
Progression of underlying diseases
Pregnancy