Studie pohybu a usazování kapek v dýchacích cestách člověka při realistických podmínkách

Study of Droplet Transport and Deposition in Human Airways under Realistic Conditions

abstrakt

en

Transport of aerosol particles in respiratory tract attracts more and more attention in view of tar-geted delivery of therapeutic sprays to treat wide spectrum of not only pulmonary diseases. To enable optical measurement of aerosol transport with air as working fluid, we created realistic thin-walled transparent airway model. The non-symmetric bifurcation model reflects real non-planar lung geometry and spans from throat to 3rd-4th generation of bronchi. A pneumatic mecha-nism generated oscillating air flow into the model. Monodisperse droplets were mixed with air at the model entry. Velocity and size measurement of the particles were done using Phase/Doppler Particle Analyzer (P/DPA). Difference between air supply from the "mouth side" and the "alveoli side" into simple bifurcation lung model was investigated. We observed increased turbulence intensity especially during expira-tion phase in case of the mouth side control compared to alveoli side control. The reason of this distinction is different pressure conditions what leads to altered conditions of turbulence genera-tion. A P/DPA measurement of aerosol transport in trachea was made for tidal volume 1 liter and breathing period 2 s. Mean axial velocity in the airway axis followed the harmonic course of gen-erated flow. Turbulence was found lower in the inspiration then in the expiration phase of the cy-cle. The turbulence was almost constant through both half cycles with exception in the time in-stants of the droplet velocity direction change. Particle deposition in the realistic airway model was studied using Positron Emission Tomography (PET). The aerosol was marked by a positron emitter 18F. Experiments were performed in steady inhalation conditions. Results show spatial distribution of the particles captured in the airway wall. Carinal ridges and surfaces with protrusions and increased roughness are typical deposition "hot spots". Data evaluation made in ROVER and R software give information on deposition quantity in particular lung sections.

V práci byl použit realistický průhledný model lidského dýchacího traktu. Byla zkoumána distribuce proudu vzduchu do jednotlivých větví dýchacího traktu pomocí průtokoměrů a pohyb aerosolu při ustáleném a cyklickém proudění pomocí PDA. K studiu depozice aerosolu byl použit PET. Byly použity režimy s různými průtoky.

Transport of aerosol particles in respiratory tract attracts more and more attention in view of tar-geted delivery of therapeutic sprays to treat wide spectrum of not only pulmonary diseases. To enable optical measurement of aerosol transport with air as working fluid, we created realistic thin-walled transparent airway model. The non-symmetric bifurcation model reflects real non-planar lung geometry and spans from throat to 3rd-4th generation of bronchi. A pneumatic mecha-nism generated oscillating air flow into the model. Monodisperse droplets were mixed with air at the model entry. Velocity and size measurement of the particles were done using Phase/Doppler Particle Analyzer (P/DPA). Difference between air supply from the "mouth side" and the "alveoli side" into simple bifurcation lung model was investigated. We observed increased turbulence intensity especially during expira-tion phase in case of the mouth side control compared to alveoli side control. The reason of this distinction is different pressure conditions what leads to altered conditions of turbulence genera-tion. A P/DPA measurement of aerosol transport in trachea was made for tidal volume 1 liter and breathing period 2 s. Mean axial velocity in the airway axis followed the harmonic course of gen-erated flow. Turbulence was found lower in the inspiration then in the expiration phase of the cy-cle. The turbulence was almost constant through both half cycles with exception in the time in-stants of the droplet velocity direction change. Particle deposition in the realistic airway model was studied using Positron Emission Tomography (PET). The aerosol was marked by a positron emitter 18F. Experiments were performed in steady inhalation conditions. Results show spatial distribution of the particles captured in the airway wall. Carinal ridges and surfaces with protrusions and increased roughness are typical deposition "hot spots". Data evaluation made in ROVER and R software give information on deposition quantity in particular lung sections.

terapeutické spreje, pohyb aerosolu, cyclické dýchání, depozice částic, dýchací cesty člověka

therapeutic sprays, aerosol transport, cyclic respiration, particle deposition, human airways

26.07.2009

University of Denver

Denver, Colorado USA

Proceedings of the 11th Triennial International Conference on Liquid Atomization and Spray Systems, Vail, Colorado USA

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