Acute Kidney Injury

Question 1

what is AKI

Answer 1

acute decline in kidney function leading to increased serum creatinine and/or reduced urinary output

Question 2

effects of Aki

Answer 2

increased serum creatinine, retention of urea, dysregulation of extracellular volume and electrolytes, reduced urinary output, impaired clearance and altered acid/base balance

Question 3

Epidemiology of AKI

Answer 3

most common in elderly,

15% of patients in hospital will develop an AKI

Question 4

3 categories of causes of AKI

Answer 4

prerenal (90%)
intrinsic renal
post renal

Question 5

prerenal causes

Answer 5

inadequate perfusion…
can be due to:
hypovolaemia, heart failure, cirrhosis, hypotension and nephrotic syndrome

Question 6

intrinsic renal causes

Answer 6

tubular damage, glomerular damage, vascular damage and interstitial damage

Question 7

post renal causes

Answer 7

obstructions due to:

bladder tumour, calculi, urethra strictures, prostatic hypertrophy or malignancy

Question 8

risk factors for developing AKI

Answer 8

age, CKD, comorbidities (heart failure etc), sepsis, hypovolaemia, haemorrhage, diabetes mellitus, exposure to nephrotoxins meds and surgery

Question 9

examples of nephrotoxic medications

Answer 9

vancomycin, NSAID’s, ACEi’s and cancer therapies

Question 10

presenting symptoms of AKI

Answer 10

hypotension, reduced urinary output, LUTS (nocturne, polyuria, dysuria), distended bladder, dehydration, dizziness etc

Question 11

investigations

Answer 11

bloods (FBC, LFT’s, U&E’s, clotting and CRP)
urinalysis (look for blood, leucocytes, protein, glucose)
immunology and virology
ultrasound (post renal causes - obstructions)
CXR (pulmonary oedema)
AXR (Kidney stones)

Question 12

principle of managing AKI

Answer 12

treating the cause. e.g. if its kidney stones causing AKI, they need to be removed

Protect patient from hyperkalaemia (calcium gluconate)
Optimise fluid balance
Stop nephrotoxic drugs
Consider for dialysis

Question 13

management of AKI

Answer 13

Monitor serum creatinine, sodium, potassium, calcium, phosphate and glucose
Identify and treat infection
Urgent relief of urinary tract obstruction
Refer to nephrology if intrinsic renal disease is suspected

Question 14

when will renal replacement therapy (RRT) be considered

Answer 14

Hyperkalaemia refractory to medical management
Pulmonary oedema refractory to medical management
Severe metabolic acidaemia
Uraemic complications

Question 15

possible complications of AKI

Answer 15

pulmonary oedema (identify using CXR),
acidaemia, 
uraemia, 
hyperkalaemia,
bleeding

Question 16

prognosis of AKI

Answer 16

Inpatient mortality varies depending on cause and comorbidities

Indicators of poor prognosis: 
Age  
Multiple organ failure  
Oliguria 
Hypotension  
CKD  

Patients who develop AKI are at increased risk of developing CKD