Improving Trendelenburg position effectiveness by varying cardiopulmonary bypass flow

Area of Science:

• Cardiovascular Surgery
• Biomedical Engineering
• Fluid Dynamics

Background:

• Trendelenburg position (TP) is utilized in cardiac surgery to mitigate cerebral air embolism.
• The combined effect of TP and varying cardiopulmonary bypass (CPB) flow on emboli transport remains incompletely understood.
• Assessing emboli load in aortic arch branch arteries (AABA) is critical for patient safety.

Purpose of the Study:

• To investigate the impact of TP and different CPB flow rates on air emboli behavior.
• To quantify trapped emboli and embolic load within the AABA under simulated surgical conditions.
• To optimize de-airing strategies during CPB by understanding emboli dynamics.

Main Methods:

• Computational fluid dynamics (CFD) simulations using a patient-specific aorta model and CPB circuit.
• Simulation of air emboli (0.1-1.0 mm) in supine and TP (-20°) at 2 L/min and 5 L/min CPB flow.
• Validation of CFD results through an aortic phantom flow experiment.

Main Results:

• TP at 5 L/min CPB flow demonstrated the lowest embolic load in the AABA for 0.1 mm emboli.
• Lower CPB flow (2 L/min) resulted in significantly more trapped emboli in both supine and TP positions.
• Flow experiments confirmed that 5 L/min CPB flow effectively transports air emboli away from the AABA, while 2 L/min promotes coalescence and trapping.

Conclusions:

• TP effectiveness in managing air emboli is significantly enhanced by optimizing CPB flow rates.
• Higher CPB flow (5 L/min) is superior in preventing air emboli from reaching the AABA.
• Findings offer valuable insights for refining emboli de-airing procedures in cardiac surgery.