Certified Hemodialysis Technologist/Technician Exam Dialysis Adequacy and Prescription 2 — Questions and Answers
Question 1: What is a patient's 'dry weight' in the context of hemodialysis?
- Weight measured after the patient is completely dehydrated
- The lowest weight a patient can tolerate without experiencing hypotension or cramps (Correct answer)
- Weight of the patient without any clothing
- Weight used to calculate Kt/V
Correct answer: The lowest weight a patient can tolerate without experiencing hypotension or cramps
Dry weight (target weight) is the post-dialysis weight at which the patient is euvolemic and does not exhibit signs of over- or under-hydration.
Question 2: The maximum recommended ultrafiltration rate to minimize intradialytic hypotension and cardiovascular stress is:
- 5 mL/kg/hour
- 10 mL/kg/hour
- 13 mL/kg/hour (Correct answer)
- 20 mL/kg/hour
Correct answer: 13 mL/kg/hour
CMS and clinical guidelines recommend keeping ultrafiltration rates below 13 mL/kg/hour to reduce cardiovascular complications and intradialytic hypotension.
Question 3: Which parameter reflects the ability of a dialyzer to clear small molecules like urea through diffusion?
- KUF (ultrafiltration coefficient)
- KoA (mass transfer area coefficient) (Correct answer)
- Membrane thickness
- Fiber bundle volume
Correct answer: KoA (mass transfer area coefficient)
KoA (mass transfer area coefficient) is the product of membrane permeability and surface area, determining diffusive clearance of small solutes.
Question 4: A dialysis patient has a pre-BUN of 80 mg/dL and a post-BUN of 20 mg/dL. What is the URR?
- 25%
- 40%
- 75% (Correct answer)
- 80%
Correct answer: 75%
(80 − 20) ÷ 80 × 100 = 60 ÷ 80 × 100 = 75%, indicating adequate dialysis.
Question 5: Which factor decreases dialysis adequacy (Kt/V) if all other parameters remain constant?
- Increasing blood flow rate
- Increasing dialysate flow rate
- Increased access recirculation (Correct answer)
- Using a higher KoA dialyzer
Correct answer: Increased access recirculation
Access recirculation reduces the effective clearance of urea by mixing dialyzed blood back into the arterial draw, lowering effective Kt/V.
Question 6: For a patient with a large body size (high V), which adjustment would best maintain adequate Kt/V?
- Decrease dialysate flow rate
- Use a smaller surface area dialyzer
- Increase treatment time or use a higher efficiency dialyzer (Correct answer)
- Reduce blood flow rate
Correct answer: Increase treatment time or use a higher efficiency dialyzer
Larger patients have a higher urea volume of distribution (V), requiring longer treatment times or higher-efficiency dialyzers to achieve adequate Kt/V.
Certified Hemodialysis Technologist/Technician Exam Dialysis Adequacy and Prescription 2
What is a patient's 'dry weight' in the context of hemodialysis?