CCP CPB Circuit Assembly & Priming 2 — Questions and Answers
Question 1: Which type of oxygenator design uses hollow fiber membranes with blood flowing on the outside (shell side) of the fibers?
- Bubble oxygenator
- Extraluminal flow membrane oxygenator (Correct answer)
- Intraluminal flow membrane oxygenator
- Disc oxygenator
Correct answer: Extraluminal flow membrane oxygenator
Extraluminal flow (shell-side) oxygenators pass gas through the fiber lumens while blood flows on the outside, providing efficient gas exchange.
Question 2: When calculating the crystalloid prime volume needed to achieve a target hematocrit during CPB, which formula element is NOT required?
- Patient blood volume
- Pre-bypass hematocrit
- Target hematocrit during CPB
- Patient's serum albumin level (Correct answer)
Correct answer: Patient's serum albumin level
Serum albumin level is not part of the dilutional hematocrit calculation, which uses patient blood volume, pre-bypass hematocrit, circuit volume, and target hematocrit.
Question 3: What is the primary purpose of incorporating a venous reservoir into the CPB circuit?
- To oxygenate venous blood before it enters the pump
- To provide volume buffer and accommodate fluctuations in venous return (Correct answer)
- To filter microemboli from the venous blood
- To maintain blood temperature during bypass
Correct answer: To provide volume buffer and accommodate fluctuations in venous return
The venous reservoir acts as a compliance chamber, buffering variations in venous return and preventing air entrainment into the arterial pump.
Question 4: During CPB circuit priming, retrograde autologous priming (RAP) is performed primarily to:
- Reduce air emboli risk during circuit assembly
- Minimize hemodilution by replacing crystalloid prime with patient blood (Correct answer)
- Increase the oncotic pressure of the prime solution
- Enhance anticoagulation before systemic heparin administration
Correct answer: Minimize hemodilution by replacing crystalloid prime with patient blood
RAP replaces crystalloid prime with the patient's own blood, reducing hemodilution and preserving hematocrit and colloid oncotic pressure.
Question 5: A perfusionist notices persistent foaming in the venous reservoir during CPB despite adequate antifoam coating. The most likely cause is:
- Excessive pump flow rate
- Air entrainment through the venous line or cannula (Correct answer)
- High oncotic pressure of the prime
- Elevated arterial line pressure
Correct answer: Air entrainment through the venous line or cannula
Persistent foaming usually indicates air entrainment via loose connections, inadvertent venting, or an inadequately placed venous cannula.
Question 6: Which prime additive is most commonly used to help maintain colloid osmotic pressure during CPB?
- Mannitol
- Albumin or hetastarch (HES) (Correct answer)
- Sodium bicarbonate
- Calcium chloride
Correct answer: Albumin or hetastarch (HES)
Albumin or hydroxyethyl starch solutions are added to the prime to partially restore colloid osmotic pressure lost with crystalloid dilution.
Question 7: When assembling a CPB circuit, the purpose of the arterial line filter (ALF) positioned distal to the pump head is to:
- Remove excess heparin from the perfusate
- Capture gaseous and particulate microemboli before they reach the patient (Correct answer)
- Regulate arterial line pressure
- Warm the blood to normothermia
Correct answer: Capture gaseous and particulate microemboli before they reach the patient
The arterial line filter traps air bubbles and particulate debris generated by the pump and oxygenator before they enter the patient's arterial circulation.
CCP CPB Circuit Assembly & Priming 2
Which type of oxygenator design uses hollow fiber membranes with blood flowing on the outside (shell side) of the fibers?