Inspiratory flow in the nose: a model coupling flow and vasoerectile tissue distensibility

Abstract

We have developed a discrete multisegmental model describing the coupling between inspiratory flow and nasal wall distensibility. This model is composed of 14 individualized compliant elements, each with its own relationship between cross-sectional area and transmural pressure. Conceptually, this model is based on flow limitation induced by the narrowing of duct due to collapsing pressure. For a given inspiratory pressure and for a given compliance distribution, this model predicts the area profile and inspiratory flow. Acoustic rhinometry and posterior rhinomanometry were used to determine the initial geometric area and mechanical characteristics of each element. The proposed model, used under steady-state conditions, is able to simulate the pressure-flow relationship observed in vivo under normal conditions (4 subjects) and under pathological conditions (4 vasomotor rhinitis and 3 valve syndrome subjects). Our results suggest that nasal wall compliance is an essential parameter to understand the nasal inspiratory flow limitation phenomenon and the associated increase of resistance that is well known to physiologists. By predicting the functional pressure-flow relationship, this model could be a useful tool for the clinician to evaluate the potential effects of treatments.

In Vitro Experiments and Numerical Simulations of Airflow in Realistic Nasal Airway Geometry

“…1,24 This phenomenon can be explained by collapse of the nasal valve due to wall compliance (not represented with this model), which induces an increase in pressure drop. Our results show that this pressure drop under baseline conditions already reaches 76% at the turbinate and only 48% at the valve, suggesting that collapse may be more marked in the deeper regions, as recently suggested by Fodil et al 6 We did not observe the same pressure drop in the left and right nasal cavities. This dissymmetry, clearly observed in the Moody diagram (Fig.…”

Simulation of airflow and aerosol deposition in the nasal cavity of a 5-year-old child

“…Factors that limit the physical realism of the current study include the assumptions of steady flow, simplified inlet conditions, a smooth and ridge airway surface, constant nasal valve aperture and glottal aperture for various breathing conditions, and a model from a single subject. Other studies have highlighted the physical significance of transient breathing (Shi et al, 2006), inlet velocity profiles (Keyhani, Scherer, & Mozell, 1995;Subramaniam, Richardson, Morgan, Kimbell, & Guilmette, 1998), nasal wall motion (Fodil et al, 2005), nasal valve change (Bridger, 1970;Bridger & Proctor, 1970) and glottal aperture variation (Brancatisano, Collett, & Engel, 1983; during respiratory maneuvers. Moreover, the nasal model in this study is based on images of a single subject acquired at the end of expiration and therefore does not account for inter-subject (Hilberg, Jensen, & Pedersen, 1993;Pickering & Beardsmore, 1999) or intrasubject (e.g., nasal cycle) (Mirza et al, 1997;Ohki et al, 2005) variability.…”

Growth of Nasal and Laryngeal Airways in Children: Implications in Breathing and Inhaled Aerosol Dynamics

“…Other studies have highlighted the physical importance of tidal breathing, 27 effects of physical activities, 27 airway wall motion, 28 and nasal valve collapse. 29 Environmental aerosols are mostly non-spherical, 30 interacting among themselves, 31 and undergo size changes due to hygroscopic effects 32 or coagulation.…”