A Method for Acoustic Stimulation of the Respiratory System
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A Method for Acoustic Stimulation of the Respiratory System S. P. Dragan*, S. M. Razinkin, and G. G. Erofeev
A method for acoustic stimulation of the respiratory system is described. The goal of the method is to increase the vital capacity of the lungs. The method is based on the interaction between an acoustic wave synchronized with breathing and the human respiratory system. The acoustic wave frequency scan is performed within a range determined by measuring the frequencysensitive absorption coefficient of the respiratory system. The scan range is selected at a level of −3 dB relative to the maximum value of the coefficient of absorption of acoustic oscilla tions.
Introduction Nondrug technologies find increasing use as a means of increasing the functional reserves of the human body. These include technologies for acoustic stimulation of the respiratory system [13]. The pleural cavity is situated between the lungs and the thoracic cage. It is a slitlike space lined with pleura. The pleura protects the lungs and prevents air from entering the thoracic cavity. It also reduces friction between the lungs and the thoracic cage. The pleural cavity is impermeable to air. The pressure in the pleural cavity is 34 mm Hg below that in the lungs. The nega tive pressure difference between the pleural cavity and the lungs is maintained during the entire inspiration, which allows the alveoli to expand and fill any addition al space provided by the expansion of the chest. With increasing pressure in the alveoli, the pressure gradient between the pleural cavity and the lungs increases. This, in turn, further opens the alveoli. For example, a 130 dB (63.2 Pa) incident wave at the entrance of the respiratory tract leads to a 416% change in the pressure gradient between the lungs and the pleural cavity. Therefore, a proportional increase in the vital capacity (VC) of the lungs can be expected. Acoustic stimulation of the respiratory system is based on the interaction of a highintensity sound wave Burnazyan Federal Medical Biophysical Center, Federal Medical Biological Agency of the Russian Federation, Moscow, Russia; Email: [email protected] * To whom correspondence should be addressed.
with the oral cavity. The impact of highintensity acoustic oscillations at resonant frequencies on the respiratory sys tem ensures the passage of sound pressure waves into all airways, which contributes to an increase in the VC by opening the “reserve” alveoli and increasing the diameter of the bronchioles.
Methods The theoretical basis of acoustic stimulation of the respiratory system is the model presentation of the respi ratory tract as a resonant sound absorber of the Helmholtz resonator type [46]. Helmholtz resonator of a complex shape serves as a mathematical model of the lungs. This model allows the dichotomous nature of pulmonary structures to be taken into account. It is assumed that the total volume of the lungs (the depth of the airways down to the alveoli) determines the reactive component of the impedance, while it
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