Inertial cavitation dose applied to two systems: Hemolysis of red blood cells and killing of bacteria cells

Inertial cavitation has been shown to generate pits in hardened metals, so it comes as no surprise that inertial cavitation can cause bioeffects. One might expect that the amount of cavitation would correlate to a bioeffect. The more cavitation there is, or the more intense the cavitation is, the greater the bioeffect. In previous work, hemolysis of red blood cells due to inertial cavitation correlated well with the inertial cavitation dose, or ICD, defined as the cumulated root mean squared broadband noise amplitude in the frequency domain between two harmonics [W. S. Chen et al., Ultrasound Med. Biol. 29 (2003)]. However, detection sensitivities and experimental approaches make ICD a relative, rather than absolute, measure of cavitation. Indeed, the cited paper states: “there is no absolute basis by which to specify how much cavitation has occurred. Nonetheless, these dose estimates yield valuable insight into mechanisms.” Perhaps even more importantly, ICD, or some other cavitation index, would be valuable to predict the end of treatment. We will examine this via the application of inertial cavitation to two simple in vitro- systems, red blood cells and bacteria cells, to illustrate the point. [Work supported in part from NIH grants R01AR080120, R01EB023910, R01GM122859, and R01EB031788.]