CHBT Dialysate Composition and Chemistry 2

Question 1

Why must acid and bicarbonate concentrates be kept separate until just before mixing in the proportioning system?

Accepted Answer

Premixing causes bicarbonate to precipitate as calcium and magnesium carbonate

Answer

When acid and bicarbonate concentrates are combined early, calcium and magnesium ions react with bicarbonate and precipitate out of solution, clogging lines and altering composition.

Question 2

What does the 'A concentrate' (acid concentrate) typically contain that is NOT in the 'B concentrate' (bicarbonate concentrate)?

Accepted Answer

Calcium, magnesium, potassium, glucose, and acetic acid or citric acid

Answer

The acid concentrate contains the divalent cations (calcium, magnesium), potassium, glucose, and an acid (acetic or citric) to keep them in solution; the B concentrate contains sodium bicarbonate.

Question 3

Sodium profiling during hemodialysis involves:

Accepted Answer

Varying the dialysate sodium concentration during treatment to improve hemodynamic stability and reduce intradialytic symptoms

Answer

Sodium profiling gradually decreases dialysate sodium from higher to lower levels during treatment, helping preserve osmolality early and reducing cramping and hypotension.

Question 4

What is the consequence of using dialysate with too low a sodium concentration?

Accepted Answer

Hyponatremia, hypotension, muscle cramps, and risk of cerebral edema

Answer

Hypotonic dialysate pulls sodium from the blood, causing hyponatremia that leads to osmotic fluid shifts, cramping, hypotension, and potentially dangerous cerebral edema.

Question 5

Acetate was largely replaced by bicarbonate as the dialysate buffer primarily because:

Accepted Answer

Acetate metabolism caused hemodynamic instability, vasodilation, and was poorly tolerated by some patients

Answer

Acetate requires hepatic metabolism to generate bicarbonate and its metabolites cause vasodilation, contributing to intradialytic hypotension and fatigue — bicarbonate dialysate is better tolerated.

CHBT - Certified Hemodialysis Bio-Medical Technician Practice Test

CHBT - Certified Hemodialysis Bio-Medical Technician Practice Test

CHBT Dialysate Composition and Chemistry 2