Effects of Carinal Ridge Shapes on Lung Airstreams

Abstract

Experimental tests cited herein have established that the deposits of inhaled particles may be highly concentrated at carinal ridges within lung bifurcations. Airway cells located at these sites will receive relatively massive doses of toxic substances and pharmacologic drugs. The deposition patterns, therefore, have immediate implications to risk assessment programs and aerosol therapy protocols. Herein, the software FIDAP was employed to study the effects of carinal ridge shapes upon fluid dynamics patterns. A series of welldefined geometric shapes (symmetric and asymmetric) were examined. For each case, a wide range of physiologically realistic flows were considered which corre-sponded to respiratory intensities for sedentary, light, and heavy activities. The results varied in a systematic manner. For example, at the lowest inspiratory flow rate of 14 L/min the effects were highly localized for all carinal ridge shapes, whereas at the highest inspiratory flow rate of 120 L/min the effects were propagated (i.e., to varying degrees) to distal regions. By relating fluid dynamics patterns to particle behavior, the results have inhalation toxicology and aerosol therapy relevance because, for example, bronchogenic carcinomas are selectively distributed within the tracheobronchial tree and certain receptors are known to be preferentially located at airway dividing sites.

Inspiratory Deposition Efficiency of Ultrafine Particles in a Human Airway Bifurcation Model

“…In the real lung, however, carinal ridges may adopt a large variety of shapes, ranging from sharp wedges to blunt profiles (Martonen et al 1994). In general, the sharper the carinal ridge, the higher are the secondary flow velocities (Heistracher and Hofmann 1995).…”

Velocity profiles in idealized model of human respiratory tract

“…Airflow in the trachea itself is further affected on its tail formed by bifurcation, where bronchial tree is divided to left and right part of lungs. Influence of this bifurcation on the shape of velocity profile was studied by Freitas and Schröder [3] and also influence of shape of the bifurcation was investigated by Martonen [4], who made an analysis on four kinds of bifurcation and prove the affect of carinal ridge on airflow fields in following generation of branching of bronchial tree. For the purposes of this study a model [5] which enables achieve more accurate measurements by Phase-Doppler Anemometry was used.…”

The evolution of inhaled particle dose modeling: A review

“…Important advances and current issues under study include: (1) individual differences (including different animal species and strains); (2) enhanced local depositions; (3) non-ideal inhaled particles e.g., non-spherical and complex shaped particles; (4) modeling the complexity of the airways, as opposed to typical paths; (5) linking upper and lower airway regions in CFD models; (6) alveolar dynamics effects on aerosol deposition (Balásházy et al, 2008;Darquenne et al, 2009;Lee & Lee, 2003); (7) consideration of secondary effects, such as airway motion, airway surface roughness, impact of collateral ventilation, and effect of disease states (e.g., Martonen, Yang, & Xue, 1994); and (8) improved software for dose calculations. The basic interactions of inhaled particles with tissue elements are an area of current interest (e.g., Gehr & Heyder, 2000), which allows modelers to identify the tissue targets and mechanisms of toxicity of inhaled aerosols.…”