Bubble rupture & viability of red blood cells under resonant acoustic standing waves

Objective: The presentation of a novel prospective treatment for scenarios where bubble presence in the bloodstream poses a clinical risk. The method relies on generating resonant acoustic standing waves within a limb to non-invasively accelerate dissolution of bubbles present in the bloodstream via bubble rupture. Additionally, a preliminary assessment of the effects of the resonant acoustic waves and bubble rupture events on red blood cell viability is provided. Methods: Two semicircular piezoelectric (PZT) transducers electrically connected to each other were assembled around a small-girth segment of a rear thigh removed from a swine specimen. When driven at the frequency of electric resonance, this swine thigh and PZT transducer arrangement generates resonant acoustic standing waves within the swine thigh. Consequently, mechanical resonance of the system was non-invasively established by monitoring the electric response of the PZT to the applied frequency. The resonant acoustic field generated was used for the detection and rupture of bubbles that travel through a simulated blood vessel installed across the swine thigh. Two sets of experiments were carried out using this methodology, one with the artificial blood vessel filled with saline solution and one with defibrinated sheep blood. For the latter case, a preliminary hematologic assessment was done with red blood cell counts. Conclusion: Resonant acoustic standing waves effectively rupture bubbles of 300µm to 900µm within a simplified swine thigh model. The average dissolved gas content was 44% due to resonant acoustic waves at powers above 20W. No significant effect on red blood cell counts was observed.