Free CCHT Technical and Environment Test 2 — Questions and Answers
Question 1: The reason potassium dialyzes and RBCs do not is:
- potassium has a larger molecular weight
- potassium has a smaller molecular weight (Correct answer)
- RBCs are not water-soluble
- RBCs have a negative charge
Correct answer: potassium has a smaller molecular weight
Dialysis works on the principle of diffusion, where solutes move across a semipermeable membrane. The size of the molecule is a critical factor in this process. Smaller molecules like potassium ions can easily pass through the pores of the dialyzer membrane, while much larger components like red blood cells (RBCs) cannot, ensuring that RBCs remain in the patient's blood.
Question 2: Acceptable limits for total chlorines in water for hemodialysis are?
- less than 0 .1mg/L (ppm) (Correct answer)
- 0.5 mg/L to 1 mg/L(ppm)
- 3.5 mg/L to 5.5 mg/L to 5.5 mg/L(ppm)
- greater than 6.0 mg/L(ppm)
Correct answer: less than 0 .1mg/L (ppm)
Chlorine and chloramines are highly toxic to hemodialysis patients, as they can cause hemolysis (destruction of red blood cells) if present in the dialysate. Therefore, strict standards are in place for water quality used in hemodialysis. The acceptable limit for total chlorines (chlorine and chloramines) in water for hemodialysis is extremely low, typically less than 0.1 mg/L (parts per million), to ensure patient safety.
Question 3: The following are factors in poor clearance during dialysis except:
- poor dialyzer reuse
- access recirculation
- low hematocrit (Correct answer)
- low blood flow rate
Correct answer: low hematocrit
Poor clearance during dialysis refers to the ineffective removal of waste products. Factors like poor dialyzer reuse (reduced efficiency), access recirculation (dialyzed blood re-entering the access), and low blood flow rate (less blood exposed to the dialyzer) directly impair the dialysis process. Low hematocrit, while indicating anemia, does not directly affect the dialyzer's ability to clear solutes from the plasma portion of the blood.
Question 4: The movement of water from an area of low solute concentration to an area of high solute concentration is called:
- diffusion
- osmosis (Correct answer)
- ultrafiltration
- dialysis
Correct answer: osmosis
Osmosis is the passive movement of water (solvent) across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration. This movement occurs to equalize the solute concentrations on both sides of the membrane. In dialysis, osmosis plays a role in fluid shifts, although ultrafiltration is the primary mechanism for controlled fluid removal.
Question 5: Potting compound, casing, fibers, and headers are part of a:
- dialysis machine
- water treatment system
- R.O. system
- dialyzer (Correct answer)
Correct answer: dialyzer
A dialyzer, often referred to as an 'artificial kidney,' is the core component of the hemodialysis system where blood purification occurs. It consists of a casing that encloses thousands of hollow fibers (the semipermeable membrane), which are sealed at each end by potting compound and held in place by headers. Blood flows through these fibers, and dialysate flows around them, facilitating the exchange of wastes and fluids.
Question 6: A hematocrit test indicates which of the following?
- Concentration of platelets
- Concentration of creatinine in the blood
- Concentration of red blood cells in the blood (Correct answer)
- Concentration of white blood cells in the blood
Correct answer: Concentration of red blood cells in the blood
A hematocrit test measures the percentage of red blood cells (RBCs) in a given volume of whole blood. It is a crucial indicator for diagnosing and monitoring anemia, a common complication in patients with kidney disease. A low hematocrit value signifies anemia, which can impact a patient's energy levels and overall health, and often requires intervention.
Question 7: In a dialysis machine, the proportioning system does what?
- Prepare the dialysate to the proper pH
- Warm the dialysate to the proper temperature
- Appropriately mix the dialysate concentrates with water (Correct answer)
- To monitor the dialysate flow rate
Correct answer: Appropriately mix the dialysate concentrates with water
The proportioning system in a dialysis machine is responsible for precisely mixing the concentrated acid and bicarbonate solutions with purified water. This ensures that the dialysate, the fluid used to remove waste products from the blood, has the correct electrolyte composition and pH for safe and effective treatment. Accurate proportioning is vital for patient safety and treatment efficacy.
Question 8: The complication in which blood has a "cherry pop" appearance is:
- blood leak
- air embolism
- hemolysis (Correct answer)
- None of the above
Correct answer: hemolysis
Hemolysis is the rupture or destruction of red blood cells, which releases hemoglobin into the plasma. When severe, this can give the blood a characteristic 'cherry red' or 'cherry pop' appearance due to the free hemoglobin. Hemolysis during dialysis is a serious complication that can be caused by various factors, including incorrect dialysate osmolarity, overheating of blood, or exposure to certain chemicals.
Question 9: The use of high sodium dialysate may predispose a patient to:
- fluid overload
- hypertension
- thirst
- All of the above (Correct answer)
Correct answer: All of the above
High sodium dialysate increases the osmotic gradient, drawing fluid from the patient's cells into the bloodstream. This expanded intravascular volume leads to fluid overload and can elevate blood pressure, causing hypertension. Additionally, the increased serum sodium stimulates thirst, prompting patients to drink more, further contributing to fluid retention.
Question 10: The capability of a dialyzer to remove fluid, expressed as ml/mmHg/hr is:
- UF Coefficient (Correct answer)
- clearance
- surface area
- priming volume
Correct answer: UF Coefficient
The Ultrafiltration (UF) Coefficient, also known as Kuf, quantifies a dialyzer's ability to remove fluid. It measures how many milliliters of fluid are removed per hour for every millimeter of mercury (mmHg) of transmembrane pressure applied. A higher UF coefficient indicates a more permeable membrane, allowing for more efficient fluid removal.
Question 11: A pre-pump arterial pressure reading is measuring:
- the pressure required to pump the blood through the dialyzer
- resistance to blood flow out of the access (Correct answer)
- pressure within the dialyzer
- None of the above
Correct answer: resistance to blood flow out of the access
A pre-pump arterial pressure reading is taken between the patient's access and the blood pump, reflecting the negative pressure required to pull blood from the access. This measurement indicates the resistance to blood flow out of the access. A more negative reading suggests increased resistance, potentially due to issues like needle occlusion, vasospasm, or access stenosis.
Free CCHT Technical and Environment Test 2
The reason potassium dialyzes and RBCs do not is: