Acoustic Droplet Vaporization Efficiency and Oxygen Scavenging in Whole Blood

Objective: Acoustic droplet vaporization (ADV) is the liquid-to-gas phase transition of perfluorocarbon (PFC) droplets to microbubbles upon ultrasound insonation. After ADV, gases dissolved in the surrounding fluid diffuse into microbubbles, enabling oxygen scavenging. Characterization of oxygen scavenging and transition efficiency (TE) in whole blood has so far been limited. In this work, oxygen scavenging and perfluorocarbon droplet TE in a saline buffer and whole bovine blood were evaluated using blood-gas analysis and flow cytometry.

Methods: Oxygen scavenging from whole blood via ADV was determined using an in vitro flow phantom with droplets comprising a phospholipid shell and either a decafluorobutane (DFB) or a perfluoropentane (PFP) core. Fluorescent droplets were used to determine ADV TE in whole blood via flow cytometry. Finally, a mathematical model predicting oxygen scavenging from whole blood was developed based on the experimental TE values.

Results: DFB droplets enabled greater oxygen scavenging and higher TE when compared with perfluoropentane droplets in both buffer and whole blood. Increasing the droplet concentration resulted in a greater amount of hemoglobin-bound and dissolved oxygen scavenging from whole blood. ADV of DFB droplets at a concentration of 5 × 10^-4 mL/mL yielded a total oxygen reduction of 913 μM. The TE decreased with increasing droplet concentration in both buffer and whole blood. Experimental oxygen scavenging data in whole blood aligned with the predicted values from the mathematical model.

Conclusion: Increased oxygen scavenging and TE were achieved with DFB droplets relative to perfluoropentane droplets.