DaVita RN Final Exam 2026/2027 Actual Exam |
Complete Questions & Verified Correct Answers |
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Section 1: Principles of Hemodialysis (15 Questions)
Q1: The primary mechanism by which urea and other small molecules are removed during
hemodialysis is:
A. Ultrafiltration
B. Diffusion [CORRECT]
C. Osmosis
D. Convection
Correct Answer: B
Rationale: Diffusion is the movement of solutes from an area of higher concentration (blood) to
an area of lower concentration (dialysate) across a semipermeable membrane. Urea, creatinine,
and other small molecules are primarily removed through this concentration gradient-dependent
process. Ultrafiltration (A) removes fluid via pressure gradient. Osmosis (C) involves water
movement. Convection (D) is solute removal during ultrafiltration (solvent drag).
Q2: A patient's pre-dialysis BUN is 80 mg/dL and post-dialysis BUN is 20 mg/dL. What is the
urea reduction ratio (URR)?
A. 25%
B. 50%
C. 75% [CORRECT]
D. 80%
Correct Answer: C
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Rationale: URR = [(Pre BUN – Post BUN) / Pre BUN] × 100 = [(80 – 20) / 80] × 100 = (60/80)
× 100 = 75%. The minimum target URR for adequate dialysis is ≥65% per KDOQI guidelines,
with ≥70% being optimal.
Q3: Which of the following dialysate components is increased to correct metabolic acidosis in
dialysis patients?
A. Sodium
B. Potassium
C. Bicarbonate [CORRECT]
D. Calcium
Correct Answer: C
Rationale: Bicarbonate in dialysate (typically 35-39 mEq/L) diffuses into the patient's blood to
correct metabolic acidosis commonly seen in ESRD. Sodium (A) affects osmolality and blood
pressure. Potassium (B) is typically 2-3 mEq/L to remove excess potassium. Calcium (D) is
adjusted for bone health and cardiac function.
Q4: The minimum acceptable standards for water quality in hemodialysis according to
AAMI/ISO include:
A. No bacterial growth allowed
B. <100 CFU/mL bacteria and <0.25 EU/mL endotoxin [CORRECT]
C. <1000 CFU/mL bacteria and <1.0 EU/mL endotoxin
D. No standards exist for water quality
Correct Answer: B
Rationale: AAMI/ISO standards require water used for dialysate preparation to contain <100
CFU/mL bacteria and <0.25 EU/mL endotoxin. Action levels are set at 50% of these maximums.
Ultrapure dialysate standards are even stricter (<0.1 CFU/mL and <0.03 EU/mL) for high-flux
dialyzers and HDF.
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Q5: During hemodialysis, the process by which water moves from an area of lower solute
concentration to higher solute concentration across a semipermeable membrane is called:
A. Diffusion
B. Ultrafiltration
C. Osmosis [CORRECT]
D. Convection
Correct Answer: C
Rationale: Osmosis is the movement of water across a semipermeable membrane from an area of
lower solute concentration to higher solute concentration. This principle is important in
understanding fluid shifts during dialysis. Diffusion (A) is solute movement. Ultrafiltration (B) is
pressure-driven fluid removal. Convection (D) is solute movement with ultrafiltration.
Q6: A patient has a Kt/V of 0.9. The nurse understands this indicates:
A. Adequate dialysis delivery
B. Inadequate dialysis delivery [CORRECT]
C. Excessive dialysis delivery
D. Normal dialysis parameters
Correct Answer: B
Rationale: The minimum target Kt/V for adequate hemodialysis is ≥1.2 per KDOQI guidelines. A
Kt/V of 0.9 indicates inadequate dialysis and requires investigation of potential causes (access
issues, blood flow problems, recirculation, shortened treatment time) and intervention.
Q7: The dialysate sodium concentration is typically set at:
A. 125-130 mEq/L
B. 136-145 mEq/L [CORRECT]
C. 150-155 mEq/L
D. Variable based only on patient preference
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Correct Answer: B
Rationale: Dialysate sodium is typically 136-145 mEq/L, individually prescribed based on
patient's serum sodium, blood pressure stability, and intradialytic symptoms. Sodium profiling
may be used to gradually decrease sodium during treatment. Too low sodium causes cramps and
hypotension; too high causes thirst and interdialytic weight gain.
Q8: Which molecule diffuses most rapidly across the dialysis membrane?
A. Albumin
B. Vitamin B12
C. Urea [CORRECT]
D. β2-microglobulin
Correct Answer: C
Rationale: Urea (MW 60 daltons) is a small molecule that diffuses rapidly across the dialysis
membrane. Smaller molecules diffuse faster than larger ones. Albumin (A, MW 66,000) is too
large. Vitamin B12 (B, MW 1,355) and β2-microglobulin (D, MW 11,800) are middle molecules
requiring high-flux dialyzers for significant removal.
Q9: Reverse osmosis (RO) water treatment systems remove which of the following? (Select all
that apply)
A. Bacteria [CORRECT]
B. Endotoxins [CORRECT]
C. Ionic contaminants [CORRECT]
D. All dissolved gases
Correct Answer: A, B, C
Rationale: Reverse osmosis removes 95-99% of bacteria, endotoxins, ionic contaminants
(sodium, calcium, magnesium, chloride), and organic chemicals. It does not remove all dissolved
gases (D), which may require degasification systems in the dialysis machine.