CDN Dialysis Adequacy and Prescription 1 — Questions and Answers
Question 1: What does the Kt/V measurement represent in hemodialysis?
- Blood flow rate times treatment volume
- Dialyzer clearance times treatment time divided by urea distribution volume (Correct answer)
- Potassium-to-volume ratio
- Fluid removal rate per treatment
Correct answer: Dialyzer clearance times treatment time divided by urea distribution volume
Kt/V is a dimensionless index where K=dialyzer urea clearance, t=treatment time, and V=patient's urea distribution volume, measuring dialysis dose.
Question 2: What is the minimum single-pool Kt/V (spKt/V) recommended by KDOQI guidelines for thrice-weekly hemodialysis?
- 0.8
- 1.0
- 1.2 (Correct answer)
- 1.4
Correct answer: 1.2
KDOQI guidelines recommend a minimum spKt/V of 1.2 for patients on thrice-weekly hemodialysis to ensure adequate uremic toxin removal.
Question 3: Which factor would most directly increase the Kt/V delivered to a patient?
- Increasing the dialysate sodium concentration
- Extending the treatment time from 3 to 4 hours (Correct answer)
- Using a larger gauge needle
- Increasing ultrafiltration rate
Correct answer: Extending the treatment time from 3 to 4 hours
Extending treatment time increases the total amount of urea cleared (K×t), thereby raising the Kt/V when urea distribution volume (V) remains constant.
Question 4: What is the primary purpose of using a high-flux dialyzer compared to a low-flux dialyzer?
- Better sodium removal
- Greater removal of middle molecules and beta-2 microglobulin (Correct answer)
- Reduced heparin requirement
- Lower blood flow requirements
Correct answer: Greater removal of middle molecules and beta-2 microglobulin
High-flux dialyzers have larger pores that allow removal of middle molecules and larger solutes like beta-2 microglobulin, which are associated with dialysis-related amyloidosis.
Question 5: A patient's pre-dialysis BUN is 80 mg/dL and post-dialysis BUN is 28 mg/dL. What is the urea reduction ratio (URR)?
- 35%
- 45%
- 65% (Correct answer)
- 72%
Correct answer: 65%
URR = [(Pre-BUN − Post-BUN) / Pre-BUN] × 100 = [(80−28)/80] × 100 = 65%, which meets the minimum recommended threshold of 65%.
Question 6: What is the recommended target URR for hemodialysis patients according to current guidelines?
- ≥50%
- ≥55%
- ≥65% (Correct answer)
- ≥80%
Correct answer: ≥65%
Current guidelines recommend a minimum URR of 65% for hemodialysis patients, corresponding to an spKt/V of approximately 1.2.
CDN Dialysis Adequacy and Prescription 1
What does the Kt/V measurement represent in hemodialysis?