CPB Circuit Assembly & Priming Flashcards

When the CPB circuit uses a closed (bladder) venous reservoir instead of an open hard-shell reservoir, which major advantage is gained?

Answer: Reduced blood-air interface and lower systemic inflammatory response activation

Closed systems minimize exposure of blood to air, reducing complement activation, platelet dysfunction, and the systemic inflammatory response compared to open hard-shell designs.

A perfusionist observes that the arterial line pressure alarm is triggering at 350 mmHg during stable CPB flow. The most likely cause is:

Answer: Partial or complete obstruction in the arterial cannula or outflow circuit

High arterial line pressure during stable flow usually indicates increased resistance distal to the pump, most commonly from cannula malposition, kinking, or partial obstruction.

What is the rationale for recirculating the CPB prime through the circuit for several minutes before initiating bypass?

Answer: To remove residual air, mix additives uniformly, and allow the circuit to equilibrate

Recirculation ensures all residual air is purged, drugs are uniformly distributed, and the circuit components are wetted and equilibrated before patient blood enters the circuit.

Which statement correctly describes the relationship between pump flow rate and roller pump RPM?

Answer: Flow depends on RPM and the tubing's cross-sectional area (stroke volume per revolution)

Roller pump output (mL/min) = RPM × stroke volume per revolution, where stroke volume is determined by the tubing's internal diameter and the head geometry.

During circuit priming for a pediatric patient, which modification to the standard adult CPB prime is most important?

Answer: Using a significantly smaller prime volume relative to the patient's blood volume to minimize hemodilution

Pediatric patients are far more sensitive to hemodilution because the circuit prime volume may equal or exceed their total blood volume, necessitating miniaturized circuits and often blood prime.

The term 'balanced ultrafiltration' during CPB refers to:

Answer: Running ultrafiltration while replacing lost volume with crystalloid to remove inflammatory mediators without changing hematocrit

Balanced ultrafiltration simultaneously removes plasma water/mediators via hemofilter while infusing crystalloid replacement, maintaining volume balance and concentrating the blood.

During CPB circuit assembly, the correct placement of a bubble detector sensor is:

Answer: On the arterial line distal to the arterial filter, as close to the patient as possible

Placing the bubble detector on the arterial line after the filter and as close to the arterial cannula as feasible maximizes detection of any air that bypasses the filter before reaching the patient.