# Prediction of Changes in Blood Parameters Induced by Low-Frequency Ultrasound
## 4 Discussion  
The results of this study show that the observed changes in the parameters provided by the blood analyzer are not only related to the formation of blood clots, but also to the effects on red blood cells (RBCs). In addition to this fundamental finding, our research also aimed to propose faster statistical and artificial intelligence methods for processing blood parameters, avoiding the mistakes of inexperienced analysts. Ultrasound affects the blood by both radiation and flow forces. High-frequency ultrasound induces aggregation of blood particles by exciting standing acoustic waves in the liquid phase of the blood, where aggregated RBCs accumulate in the nodes. The aggregation of human RBCs is the major cause of a wide range of pathological conditions, from bacterial infections to cancer. In contrast to the standing waves caused by high-frequency ultrasound, low-frequency traveling acoustic waves cause the opposite phenomenon--the dissociation or mixing of RBC aggregates. Since blood is a shear-thinning fluid with complex reactions that strongly depend on the formation of aggregates by its components such as RBCs, the dissociation of RBC aggregates under the influence of low-frequency ultrasound begins as the shear rate increases above a critical value of \(\gamma\) = 5-10 s\({}^{-1}\)[29]. Therefore, during blood analyzer tests, it was found that the number of single erythrocytes separated from aggregates by low-frequency ultrasound in the volume of a blood analyzer drop was higher than in the same volume of erythrocyte aggregates not affected by ultrasound.  
Blood tests revealed that several parameters, such as mean corpuscular hemoglobin (MCH), the mean corpuscular hemoglobin concentration (MCHC), and platelet aggregation (PLT), show the greatest changes during exposure to low-frequency ultrasound and exceeded the permissible limits. The MCH and MCHC parameters indicate the amount of hemoglobin per cell and the amount of hemoglobin per unit volume, respectively. Hemoglobin is required to transport oxygen from the lungs to the cells of the body. Ultrasound has an impact on changes in these blood parameters related to RBC functions. During this study, venous blood was drawn from a vein near the elbow for laboratory purposes. Venous blood is low in oxygen. When ultrasound was used on dissociated erythrocytes in an open sample (surrounded by oxygen in a Vacuette K2E K2 EDTA 13 \(\times\) 75 tube) and the shear rate exceeded a critical value, the color of the dissociated erythrocytes changed to a bright red color, as if they had been enriched by oxygen, as in the case of arterial blood. An important property of hemoglobin is that O\({}_{2}\) binding is pH-dependent. It has been experimentally observed that CO\({}_{2}\) is released more readily when the pH is acidic, i.e., when there are high concentrations of CO\({}_{2}\). This was the case for our blood samples before treatment with low-frequency ultrasound. This treatment has the potential to render hemoglobin more conducive to binding, with CO\({}_{2}\) providing energy for the dispersion of gas bubbles within membranes or the fusion of multiple RBC membranes [30].  
The key finding of this study was the observation of changes in gas exchange in the blood under the influence of different intensities of low-frequency ultrasound. This finding  
Figure 9: Feature importance scores (\(F\) scores) using the \(F\)-test algorithm for the PLT value prediction including 180 W, 180 M, and 180 H signals. (**a**) 180 W US signal. (**b**) 180 H US signal. (**c**) 180 M US signal.  
holds potential implications for treating pulmonary hypertension using the low-frequency ultrasound transducer developed (patent pending) by the authors of this article [25].