Generation of microbubbles in extracorporeal life support and assessment of new elimination strategies

Area of Science:

• Cardiovascular Engineering
• Biomedical Engineering
• Medical Device Technology

Background:

• Microbubbles (MB) are a significant complication in venoarterial extracorporeal life support (ECLS), potentially leading to severe clinical issues.
• Effective detection and elimination of MB are crucial for patient safety during ECLS procedures.

Purpose of the Study:

• To develop an in vitro ECLS setup for controlled generation and detection of MB.
• To evaluate the efficacy of different strategies for MB elimination within the ECLS circuit.

Main Methods:

• An in vitro ECLS model was simulated using a centrifugal pump, membrane oxygenator, and occluder, primed with a 44% glycerin solution.
• MB were generated by occluding the pump's inflow line under static or dynamic conditions at varying revolution speeds (2500-3400 rpm).
• MB detection was performed using a bubble counter, and the elimination capacities of the oxygenator and dynamic bubble traps (DBTs) were assessed.

Main Results:

• MB generation was strongly correlated with negative pressure at the inflow line, pump speed, and inflow restriction, with the centrifugal pump identified as a major source.
• The membrane oxygenator demonstrated limited capacity for retaining larger MB.
• The implementation of one or more DBTs significantly reduced MB count and total gas volume, particularly at high flow rates.

Conclusions:

• Centrifugal pumps in ECLS circuits are a primary source of microbubble generation, influenced by operational parameters like speed and inflow restriction.
• Dynamic bubble traps are effective in significantly reducing microbubble load and gas volume in ECLS systems.
• DBTs can facilitate the breakdown of larger microbubbles, promoting their absorption and improving circuit safety.