Oliguria And Renal Failure

Question 1

Definition of oliguria

Answer 1

Urine output < 0.5 mL/kg/hr
Warning if oliguria > 2 hours - may lead to acute renal failure
Warning sign of reduced perfusion

Question 2

Pathophysiology

Answer 2

Outer renal medulla prone to ischaemia
(due to countercurrent exchange anatomical arrangement)
Reduced renal blood flow
Structural changes -> acute tubular necrosis

Question 3

Causes of AKI

Answer 3

Pre-existing renal impairment - DM, HTN, renovascular disease

Renal hypoperfusion
- Hypovolaemia
- Shock
- Aortic surgery
- Sepsis
- Hepato renal syndrome

Nephrotoxins - aminoglycosides, glycopeptides, NSAIDS

Rhabdomyolysis, cholesterol embolism, hypercalcaemia

Intrinsic renal disease

Obstruction - stones, papillary necrosis

Question 4

Management of AKI

Answer 4

Resuscitation
Treat infection
Avoid nephrotoxic drugs
Relief obstruction

Question 5

Investigations

Answer 5

RP
CK
ABG
UFEME
US kidneys

Question 6

Resuscitation

Answer 6

Correct hypovolaemia
Restore cardiac output - May require inotropes
Restore perfusion pressure - up to MAP > 80

Question 7

Side Effects of Dopamine

Answer 7

Tachyarrhythmias
Exacerbates renal and mesenteric ischaemia
Impairs immune function

Question 8

Trial of furosemide

Answer 8

Reduces juxtamedullary oxygen consumption

But does not improve creatinine clearance or affect survival

Causes diuresis

Trial only after adequate volume resuscitation

Question 9

Established AKI

Answer 9

Rising creatinine persistently
Refractory oliguria
Acidosis

Question 10

Management of fluid in AKI

Answer 10

Previous hour urine output + 30mL

Treat hyperkalaemia, acidosis, volume overload