Acute Kidney Injury Flashcards
What 3 Ix are used to interrogate the cause of AKI?
Fluid stasis
Urine analysis
Ultrasound
Outline the pathophysiology of ATN
Ischaemia > Depletion of ATP > Release of ROS > apoptosis > cell desquamation > obstructive casts
What are the implications of anuria vs oliguria for the cause of AKI?
Anuria - more likely complete obstruction, major vascular catastropy, severe ATN
Oliguria - less severe
How might you differentiate pre-renal and intrinsic causes of AKI?
Osmolarity will be >500 in pre-renal but <350 in intrinsic as its lost its concentrating ability. Similarly the urine salt will be high in intrinsic
Look for cast in urine for intrinsic (prerenal urine is normal)
What does STOP stand for as to the causes of AKI?
Sepsis and hypovolaemia
Toxins
Obstructions
Parenchyma disease
What are the three phases of ATN?
Initiation - Acute drop in GFR and initial rise in Cr
Maintenance - GFR remains low, Cr and Urea rise significantly
Recovery - Tubular function is restored and Cr drops
How is hyperkalaemia treated?
Insulin and glucose
Calcium gluconate (stabilise the heart)
Resonium
Dialysis
What are some post renal causes of AKI?
Prostate enlargement
Uteric strictures
Tumours
Surgical disruption
Bilateral caliculi
What should be done if AKI occurs?
Remove the offending agent
Meticulous fluid balance - volume overload is bad
Measure urea, creatinine and other electrolytes
Daily weights
What is the major difference between haemodialysis and haemofiltration?
Haemodialysis works via osmosis
Haemofiltration works by ultrafiltration
What are some prerenal causes of AKI?
Hypovolaemia - Bleeding, GI loss, inappropriate replacement post op, diuretics, 3rd space loss
Cardiogenic - acute fall in CO
Sepsis
Neurogenic
How can intrinsic causes of AKI be subcharacterised?
- Tubular injury eg ATN
- Interstitial Injury eg drugs, infection
- Glomerular injury
- Vascular disease - eg vasculitis
How long does it take to recover from ATN?
2-6 weeks
Is anuria always a feature of ATN?
No, urine output can still occur
How do you evaluate if a kidney injury is acute or chronic?
Look at pre-existing conditions
Look at previous Cr levels
US of kidneys
Outline the diagnostic criteria for AKI
Stage I - Creatinine increase by 25umol/L or 150-200%
- Urine output <0.5ml/kg/hour for > 6hours
Stage II - Creatinine increase 200 - 300% from baseline
- Urine output <0.5ml/kg/hour > 12 hours
Stage III - Creatinine increase >300% or >350umol/L after an increase of 50umol/L
- Urine output <0.3ml/kg/hour for > 24 hours or anuria for > 12hours
