In medicine, high-frequency ultrasound (US) from I to 10 MHz is used for both diagnostic and therapeutic purposes. Acoustic waves emitted by high-frequency US are standing waves, which have a limited penetration depth into the body, so external tissues are more affected by high-frequency US than internal organs. The peculiarity of standing acoustic waves is that they accumulate red blood cells (RBC) in nodal points, i.e. aggregate them. For the first time in medical practice, using a blood analyzer, with the help of artificial intelligence algorithms, the influence of low-frequency US of various intensity and duration on hemodynamic parameters was determined, revealing the possibility of dissociation of RBC aggregates [1]. This occurs due to traveling acoustic waves induced by low-frequency US, when hemoglobin molecules enhance gas exchange at the respiratory surfaces across the entire surface area of the dissociated RBCs.
The safety of US exposure is very important for the patient’s health. According to the standard of the Ultrasound Society, the level of acoustic intensity emitted by medical ultrasound diagnostic equipment in the frequency range 1-10 MHz must not exceed 1000 mW/ cm2. Bearing in mind that as the ultrasound frequency decreases, its wavelength increases, and at the same time the penetration, low-frequency (up to 100 kHz) US is more suitable for non-invasive therapy, but there is a lack of effective means for creating such an acoustic effect. The acoustic intensity decreases exponentially and proportionally to the tissue attenuation coefficient of the biological medium and the depth of action. In contrast to commonly used ultrasonic transducers that exclusively generate only longitudinal modes of vibration, using digital twins our developed and patented low-frequency piezoelectric transducer [2] operates in a radial mode of vibration. This radial displacement increases the penetration of the acoustic signal, reduces the dispersion of the signal, and allowes to increase the acoustic effect in deeper biological tissues, so the developed device could be adapted for therapeutic purposes.
The measurements of the physiological parameters of anesthetized sheep showed that the penetration of the ultrasonic waves through the biological tissues emitted by our developed device is 4 times higher than that of the devices used so far [3]. The decrease in blood pressure occurs due to the decreased number of single RBCs per unit volume of blood exposed to low-frequency US compared to the number of RBCs in aggregates of blood not affected by ultrasound. This significantly reduces blood viscosity as the viscosity of human blood is directly proportional to the haematocrit (the concentration of RBCs), which is responsible for the transport of oxygen and carbon dioxide. In vivo studies in sheep showed a greater than 10-15% improvement in lung oxygen saturation and a reduction in blood pressure and heart rate within 7 minutes.
The applications of the revealed hemodynamic features and the developed equipment in future could be associated with the possibilities of heart valve plaques destruction by precisely focusing a low-frequency acoustic signal on them, promoting wound healing or making the healing process more efficient by directing the drugs encapsulated in RBCs to a specific organs of the human body. The possibility of breaking up biofilms with ultrasound, making the antibiotics more effective, as well as the improvment brain circulation by additional carbon dioxide are also promising, because as a result of low-frequency exposure, hemoglobin transports not only more oxygen from the lungs, but also carbon dioxide from biotissues.
JOURNAL REFERENCE
1. Ostasevicius V, Paulauskaite-Taraseviciene A, Lesauskaite V, Jurenas V, Tatarunas V, Stankevicius E, Tunaityte A, Venslauskas M, Kizauskiene L. Prediction of changes in blood parameters induced by low-frequency ultrasound, Appl Syst Innov, 2023, 6(6), 99; DOI: https://doi.org/10.3390/asi6060099
2. Ostasevicius V, Jurenas V, Mikuckyte S, Vezys J, Stankevicius E, Bubulis A, Venslauskas M, Kizauskiene L. Development of a low frequency piezoeectric ultrasonic transducer for biological tissue sonication. Sensors, 2023; 23 (7): 1-16. https://doi.org/10.3390/s23073608
3. Ostasevicius V, Jurenas V, Venslauskas M, Kizauskiene L, Zigmantaite V, Stankevicius E, Bubulis A, Vezys J, Mikuckyte S. Low-frequency ultrasound for pulmonary hypertension therapy, Respiratory Research, Springer Nature, 2024; 70(25): 1-12. https://doi.org/10.1186/s12931-024-02713-5
ABOUT THE AUTHOR
Prof. Dr.Hab. Vytautas Ostasevicius, academician of the Lithuanian and Royal Swedish Academies of Sciences, director of the Mechatronics Institute of the Kaunas University of Technology, professor. Specializes in the development of mechatronic ultrasonic devices. Out of 15 books written by him, 3 are published by Springer Nature. He is the author of 150 scientific articles and 50 inventions/patents. His scientific research is related to the application of Digital Twins and Artificial Intelligence methods for the development of technological and biomechanical systems. He was leader of hi-tech projects: “Non-invasive Device and Methods to Treat Pulmonary Hypertension and Acute Respiratory Distress Syndrom”, „Healthy Aging“, “High Technologies for Human Health”, “Development of Methods and Equipment for Human Active Movement Monitoring“, “Development of the Sensor System Technology to Monitor Human Physiological Data Employing MEMS, IT and Smart Textiles Technologies”. During the implementation of these projects, health problems were studied, dozens of devices for improving human health were designed, manufactured and patented.
