CHBT Dialysate Composition and Chemistry 1 — Questions and Answers
Question 1: What is the purpose of bicarbonate in hemodialysis dialysate?
- To correct metabolic acidosis by providing a buffer that crosses into the patient's blood (Correct answer)
- To prevent bacterial growth in the dialysate
- To remove excess potassium
- To lower dialysate conductivity
Correct answer: To correct metabolic acidosis by providing a buffer that crosses into the patient's blood
Bicarbonate in dialysate diffuses across the membrane into the blood, replacing bicarbonate lost to ESRD-associated metabolic acidosis and restoring acid-base balance.
Question 2: Why is glucose often added to hemodialysis dialysate?
- To prevent hypoglycemia during treatment and reduce glucose loss across the membrane (Correct answer)
- To increase dialysate osmolality for ultrafiltration
- To serve as an energy source for the dialyzer membrane
- To inhibit bacterial growth
Correct answer: To prevent hypoglycemia during treatment and reduce glucose loss across the membrane
Adding glucose (typically 100–200 mg/dL) to dialysate helps prevent intradialytic hypoglycemia and reduces net glucose loss, particularly in diabetic patients.
Question 3: What is the typical sodium concentration range in hemodialysis dialysate?
- 135–145 mEq/L (Correct answer)
- 100–115 mEq/L
- 150–165 mEq/L
- 120–130 mEq/L
Correct answer: 135–145 mEq/L
Dialysate sodium is typically maintained at 135–145 mEq/L to approximate normal plasma sodium and avoid hypo- or hypernatremia during treatment.
Question 4: Which ion in dialysate is primarily responsible for controlling dialysate conductivity?
- Sodium (Correct answer)
- Potassium
- Calcium
- Bicarbonate
Correct answer: Sodium
Sodium is present in the highest concentration in dialysate and contributes most to overall ionic conductivity, making it the primary determinant of conductivity readings.
Question 5: What happens if dialysate calcium is set too high for a patient?
- Hypercalcemia, potentially causing cardiac arrhythmias, vascular calcification, and soft tissue deposits (Correct answer)
- Hypocalcemia and tetany
- Metabolic acidosis
- Hemolysis
Correct answer: Hypercalcemia, potentially causing cardiac arrhythmias, vascular calcification, and soft tissue deposits
Excess calcium transferred from dialysate to blood causes hypercalcemia, which can trigger arrhythmias, worsen vascular calcification, and cause soft tissue mineral deposits.
Question 6: The potassium concentration in hemodialysis dialysate is typically set at:
- 1–4 mEq/L, individualized to the patient's pre-dialysis serum potassium (Correct answer)
- 0 mEq/L for all patients
- Equal to normal plasma potassium (3.5–5.0 mEq/L) for all patients
- 8–10 mEq/L to prevent hypokalemia
Correct answer: 1–4 mEq/L, individualized to the patient's pre-dialysis serum potassium
Dialysate potassium is individualized based on pre-treatment serum levels to safely remove excess potassium without causing dangerous hypokalemia.
CHBT Dialysate Composition and Chemistry 1
What is the purpose of bicarbonate in hemodialysis dialysate?