Gaseous microemboli sizing in extracorporeal circuits using ultrasound backscatter

Area of Science:

• Biomedical Engineering
• Acoustics
• Medical Devices

Background:

• Gaseous microemboli (GME) pose risks during extracorporeal procedures like cardiopulmonary bypass (CPB).
• Accurate sizing of GME is crucial for assessing embolic load and patient risk.
• Current methods for GME detection and sizing in CPB circuits have limitations.

Purpose of the Study:

• To develop and validate a method for estimating the size of gaseous microemboli (GME) in extracorporeal blood circuits.
• To establish a correlation between ultrasound backscattered echo amplitude and GME diameter.
• To assess the feasibility of using ultrasound for real-time GME sizing during CPB.

Main Methods:

• Analytical modeling of GME ultrasound scattering behavior in blood.
• Computer simulations using acoustic finite integration technique.
• In vitro ultrasonic and microscopic measurements of GME in a test circuit.
• Validation in a closed-loop CPB circuit with canine blood.

Main Results:

• A linear relationship was predicted between GME diameter and backscattered ultrasound echo amplitude.
• Simulations showed minor deviations from linearity, treatable as random scatter.
• Experimental validation confirmed a strong linear correlation between echo amplitude and GME diameter.
• The method was validated under CPB conditions with high flow rates.

Conclusions:

• Ultrasound backscattered echo amplitude is a viable method for accurately estimating GME size distribution.
• This technique can quantify embolic load delivered to patients during CPB.
• The proposed ultrasonic sizing method offers a promising approach for enhanced patient safety in CPB procedures.