Extracorporeal shock waves act by shock wave-gas bubble interaction

Area of Science:

• Biophysics
• Acoustics
• Hematology

Background:

• Extracorporeal shock wave lithotripsy (ESWL) involves high-energy acoustic waves.
• Hemoglobin release from red blood cells (RBCs) is a key indicator of shock wave-induced cell damage.
• Previous research suggested static excess pressure minimizes RBC damage during ESWL, potentially due to shock wave-gas bubble interactions.

Purpose of the Study:

• To further investigate the mechanism behind reduced hemoglobin release under static excess pressure.
• To substantiate the role of shock wave-gas bubble interaction in mitigating RBC damage.
• To analyze the effect of shock wave frequency and pressure on hemoglobin release.

Main Methods:

• Human red blood cells (RBCs) were suspended in a lithotripter.
• Shock waves were applied at a lower frequency (1 pulse/5 s) and as single or double pulses at 30 kV.
• Experiments were conducted at various static excess pressures (0-200 kPa) and ambient pressure.

Main Results:

• Lower shock wave frequency (1 pulse/5 s) reduced hemoglobin release compared to 1 pulse/s, particularly at 0-100 kPa.
• A single shock wave caused minimal hemoglobin release at ambient and 200 kPa.
• Two shock waves increased hemoglobin release at ambient pressure but minimally at 200 kPa, suggesting pressure-dependent interaction.

Conclusions:

• Results provide strong evidence for shock wave-gas bubble interaction as the primary mechanism influencing RBC damage.
• Static excess pressure significantly mitigates shock wave-induced hemoglobin release.
• Optimizing shock wave parameters and pressure may reduce cell damage in lithotripsy and other applications.