Acute Renal Failure

Question 1

Is ARF reversible?

Answer 1

Yes, this is reversible l/o renal fx

Question 2

What are 2 problems that ARF can results in?

Answer 2

• Fluid ‘lytes imbalance

- Azotemia

Question 3

Compare oliguria to anuria

Answer 3

• Oliguria: 100 - 400 ml urine output/day

- Anuria: < 100 ml urine output/day

Question 4

What is the min urine output per day required to avoid azomtemia?

Answer 4

400 ml

Question 5

What are 3 Et categories for ARF? What is ARF usually a result of?

Answer 5

• Prerenal
• Intrarenal
  
  • 80-90% is due to the above 2
• Postrenal
• Usually a result of hypotension and/or hypovolemia

Question 6

What is the patho for prerenal ARF?

Answer 6

• e.g. volume deficit ->decreased renal perfusion -> ischemia & oliguria

Question 7

Intrarenal ARF has 3 phases, explain each:

Answer 7

1. Initiating phase
   - Extends from the precipitating event (e.g. trauma) to
   tubular injury
2. Maintenance phase
   - There is significantly diminished GFR
   - Oliguria, edema, azotemia
3. Recovery phase
   - Repair commences with gradual ↑ in GFR

Question 8

What is the patho for postrenal ARF?

Answer 8

E.g. BPH followed by hydronephrosis

Question 9

What are the mnfts of ARF?

Answer 9

• Oliguria / anuria
• Fluid-elect imbalance
• Azotemia, proteinuria, hematuria
• Edema, HTN (consider these as cmplx)

Question 10

What is the RIFLE classification?

Answer 10

Risk, Injury, Failure, Loss, End stage renal disease

- RIFLE uses urine output, GFR & creatinine

Question 11

Other than RIFLE, what is another Dx option for ARF?

Answer 11

• Newer biomarkers (e.g. IL-18) are being investigated.
  
  • IL-18 is produced in the proximal tubule following
    ischemic injury (could be a good earlier marker)

Question 12

What dietary modifications are implemented to treat ARF?

Answer 12

• Restrict protein intake to limit nitrogenous wastes

- Cautious fluid and ‘lyte replacement

Question 13

What kinds of intermittent dialysis are used to treat ARF?

Answer 13

Both hemodialysis & peritoneal dialysis

Question 14

What is Continuous Renal Replacement Therapy?

Answer 14

• Takes place in ICU setting over 24hr
• Involves various blood purification techniques
  
  • Convection (hemofiltration)
    - Removes high molecular weight
    substances
  • Diffusion (hemodialysis)
    - Removes low molecular weight substances
  • Hemodiafiltration combines the above two

Question 15

If ARF goes untreated, it will become ______ _____ _____.

Answer 15

Chronic renal failure

- Progressive, irreversible kidney damage

Question 16

What are the 3 stages of chronic renal failure?

Answer 16

1. Diminished renal reserve
   - GFR falls below 50% of normal (N = 120-130 ml/min)
   - No obvious signs of impaired renal Fx
2. Renal insufficiency
   - GFR between 20% - 50% of normal
3. Renal failure
   - GFR < 20%•GFR < 5% = end stage renal failure