DAVITA RN FINAL EXAM COMPLETE 250
QUESTION PRACTICE EXAM AND ANSWERS
WITH DETAILED RATIONALES LATEST
UPDATE THIS YEAR
SECTION 1: PRINCIPLES OF HEMODIALYSIS (Questions 130)
Question 1
During hemodialysis, urea moves from the blood compartment to the dialysate
compartment primarily through which mechanism?
A) Ultrafiltration
B) Convection
C) Diffusion
D) Osmosis
Correct Answer: C) Diffusion
Rationale: Diffusion is the primary mechanism for solute removal in hemodialysis.
Urea and other small molecular weight solutes move across the semipermeable
membrane from an area of higher concentration (blood) to lower concentration
(dialysate) along the concentration gradient.
,Question 2
A patient's predialysis BUN is 80 mg/dL and postdialysis BUN is 20 mg/dL. What
is the urea reduction ratio (URR)?
A) 25%
B) 50%
C) 75%
D) 80%
Correct Answer: C) 75%
Rationale: URR = [(PreBUN PostBUN) / PreBUN] × 100 = [(80 20) / 80] × 100
= (60/80) × 100 = 75%. Adequate dialysis typically targets URR ≥ 6570%.
Question 3
Which dialysate component is increased to correct metabolic acidosis in dialysis
patients?
A) Sodium
B) Potassium
C) Bicarbonate
D) Calcium
Correct Answer: C) Bicarbonate
,Rationale: Bicarbonate is added to dialysate to correct metabolic acidosis by
diffusing into the blood. Sodium affects osmolality, potassium is adjusted based on
serum levels, and calcium affects bone metabolism and cardiac function.
Question 4
What is the minimum acceptable standard for water quality in hemodialysis
according to AAMI/ISO?
A) No bacterial growth allowed
B) < 100 CFU/mL bacteria and < 0.25 EU/mL endotoxin
C) < 1000 CFU/mL bacteria
D) No standards exist for water quality
Correct Answer: B) < 100 CFU/mL bacteria and < 0.25 EU/mL endotoxin
Rationale: AAMI/ISO standards require water for dialysis to have < 100 CFU/mL
bacteria and < 0.25 EU/mL endotoxin. Option A is unrealistic, Option C exceeds
standards, and Option D is incorrect.
Question 5
Which factor primarily drives ultrafiltration during hemodialysis?
A) Dialysate flow rate
B) Transmembrane pressure (TMP)
, C) Blood flow rate
D) Dialysate temperature
Correct Answer: B) Transmembrane pressure (TMP)
Rationale: Ultrafiltration is driven by transmembrane pressure—the pressure
gradient between the blood compartment and dialysate compartment. Higher TMP
increases fluid removal.
Question 6
A patient requires removal of 3.5 kg of fluid during a 4hour dialysis treatment.
What is the required ultrafiltration rate?
A) 500 mL/hr
B) 875 mL/hr
C) 1,000 mL/hr
D) 1,200 mL/hr
Correct Answer: B) 875 mL/hr
Rationale: Ultrafiltration rate calculation: 3.5 kg = 3,500 mL. 3,500 mL ÷ 4 hours
= 875 mL/hr. The ultrafiltration rate should generally not exceed 1013 mL/kg/hr to
minimize intradialytic hypotension and cramping.
QUESTION PRACTICE EXAM AND ANSWERS
WITH DETAILED RATIONALES LATEST
UPDATE THIS YEAR
SECTION 1: PRINCIPLES OF HEMODIALYSIS (Questions 130)
Question 1
During hemodialysis, urea moves from the blood compartment to the dialysate
compartment primarily through which mechanism?
A) Ultrafiltration
B) Convection
C) Diffusion
D) Osmosis
Correct Answer: C) Diffusion
Rationale: Diffusion is the primary mechanism for solute removal in hemodialysis.
Urea and other small molecular weight solutes move across the semipermeable
membrane from an area of higher concentration (blood) to lower concentration
(dialysate) along the concentration gradient.
,Question 2
A patient's predialysis BUN is 80 mg/dL and postdialysis BUN is 20 mg/dL. What
is the urea reduction ratio (URR)?
A) 25%
B) 50%
C) 75%
D) 80%
Correct Answer: C) 75%
Rationale: URR = [(PreBUN PostBUN) / PreBUN] × 100 = [(80 20) / 80] × 100
= (60/80) × 100 = 75%. Adequate dialysis typically targets URR ≥ 6570%.
Question 3
Which dialysate component is increased to correct metabolic acidosis in dialysis
patients?
A) Sodium
B) Potassium
C) Bicarbonate
D) Calcium
Correct Answer: C) Bicarbonate
,Rationale: Bicarbonate is added to dialysate to correct metabolic acidosis by
diffusing into the blood. Sodium affects osmolality, potassium is adjusted based on
serum levels, and calcium affects bone metabolism and cardiac function.
Question 4
What is the minimum acceptable standard for water quality in hemodialysis
according to AAMI/ISO?
A) No bacterial growth allowed
B) < 100 CFU/mL bacteria and < 0.25 EU/mL endotoxin
C) < 1000 CFU/mL bacteria
D) No standards exist for water quality
Correct Answer: B) < 100 CFU/mL bacteria and < 0.25 EU/mL endotoxin
Rationale: AAMI/ISO standards require water for dialysis to have < 100 CFU/mL
bacteria and < 0.25 EU/mL endotoxin. Option A is unrealistic, Option C exceeds
standards, and Option D is incorrect.
Question 5
Which factor primarily drives ultrafiltration during hemodialysis?
A) Dialysate flow rate
B) Transmembrane pressure (TMP)
, C) Blood flow rate
D) Dialysate temperature
Correct Answer: B) Transmembrane pressure (TMP)
Rationale: Ultrafiltration is driven by transmembrane pressure—the pressure
gradient between the blood compartment and dialysate compartment. Higher TMP
increases fluid removal.
Question 6
A patient requires removal of 3.5 kg of fluid during a 4hour dialysis treatment.
What is the required ultrafiltration rate?
A) 500 mL/hr
B) 875 mL/hr
C) 1,000 mL/hr
D) 1,200 mL/hr
Correct Answer: B) 875 mL/hr
Rationale: Ultrafiltration rate calculation: 3.5 kg = 3,500 mL. 3,500 mL ÷ 4 hours
= 875 mL/hr. The ultrafiltration rate should generally not exceed 1013 mL/kg/hr to
minimize intradialytic hypotension and cramping.
