CHT Certified Hemodialysis Technologist/Technician 4 — Questions and Answers
Question 1: Which anticoagulant is most commonly used to prevent clotting in the extracorporeal circuit during hemodialysis?
- Warfarin
- Unfractionated heparin (Correct answer)
- Aspirin
- Enoxaparin
Correct answer: Unfractionated heparin
Unfractionated heparin is the standard anticoagulant for hemodialysis circuits due to its short half-life and reversibility with protamine sulfate.
Question 2: A technician notices the venous pressure alarm is consistently high during a treatment. This most likely indicates:
- A kinked arterial line
- Stenosis or clotting near the venous needle site (Correct answer)
- Low heparin levels in the circuit
- High blood flow rate through a properly functioning fistula
Correct answer: Stenosis or clotting near the venous needle site
Elevated venous pressure indicates resistance to blood return, commonly caused by stenosis, needle malposition, or clotting at the venous access site.
Question 3: Hemolysis during hemodialysis can be caused by:
- High dialysate bicarbonate
- Kinked blood tubing or excessive blood pump speed (Correct answer)
- Low blood flow rate below 200 mL/min
- High transmembrane pressure
Correct answer: Kinked blood tubing or excessive blood pump speed
Mechanical destruction of red blood cells can occur due to kinked tubing, stenotic needles, or excessively high pump speeds creating shear stress.
Question 4: The buttonhole cannulation technique for AVF access involves:
- Rotating needle insertion sites each session
- Inserting needles into the same tract using a blunt needle after the tract forms (Correct answer)
- Using a tourniquet to engorge the vessel before cannulation
- Only using sharp needles for cannulation
Correct answer: Inserting needles into the same tract using a blunt needle after the tract forms
Buttonhole technique creates a consistent scar tunnel allowing blunt needle entry, reducing hematoma risk and patient discomfort.
Question 5: Which dialyzer membrane characteristic most directly affects the removal of middle molecules like beta-2 microglobulin?
- Membrane surface area
- Membrane thickness
- Pore size (high-flux vs. low-flux) (Correct answer)
- Membrane material (cellulose vs. synthetic)
Correct answer: Pore size (high-flux vs. low-flux)
High-flux membranes have larger pores that allow convective removal of middle molecules such as beta-2 microglobulin, which low-flux membranes cannot adequately clear.
Question 6: A patient's dry weight is best described as:
- The patient's weight immediately after dialysis
- The weight at which the patient has no signs of fluid overload or dehydration (Correct answer)
- The patient's normal body weight without the dialysis machine connected
- The weight determined solely by the patient's BMI
Correct answer: The weight at which the patient has no signs of fluid overload or dehydration
Dry weight is the target post-dialysis weight at which the patient is euvolemic — no edema and no signs of intravascular volume depletion.
Question 7: A concentrate proportioning system that uses two concentrate containers (acid and bicarbonate) is called:
- Single-bath system
- Bicarbonate dialysate delivery system (Correct answer)
- Acetate-based proportioning
- Fixed-ratio concentrate mixer
Correct answer: Bicarbonate dialysate delivery system
Modern bicarbonate dialysate delivery systems use separate acid (containing acetate, electrolytes, dextrose) and bicarbonate concentrates to produce dialysate online.
CHT Certified Hemodialysis Technologist/Technician 4
Which anticoagulant is most commonly used to prevent clotting in the extracorporeal circuit during hemodialysis?