Insights into exercise-induced rhinitis based on nasal aerodynamics induced by airway morphology

Abstract

Background: Exercise-induced rhinitis (EIR) is a poorly understood phenomenon that may be related to increased inspiratory airflow. Characterization of the development of EIR is important to understand contributing factors.

Objective: To characterize how different nasal morphologies respond to airflow-related variables during rapid/deep inspiratory conditions.

Methods: Subject-specific nasal airways were reconstructed from radiographic images. Unilateral airways were classified as Standard, Notched, or Elongated accord to their distinct nasal vestibule morphology. Computational fluid dynamics simulations were performed at various airflow rates.

Results: For all simulated flow rates, average resistance at the nasal vestibule, airflow velocity and wall sheer stress were highest in Notched. Average mucosal heat flux was highest in Standard. Notched phenotypes showed lower mean percent increases from 10 L/min to 50 L/min in all computed variables.

Conclusion: Resistance values and airflow velocities depicted a more constricted nasal vestibule in the Notched phenotypes, while perception of nasal mucosal cooling (heat flux) favored the Standard phenotypes. Different nasal phenotypes may predispose to EIR.

Keywords: Computational fluid dynamics; Exercise-induced hypersensitivity; Nasal hyperreactivity; Nasal obstruction; Rhinitis; Sports medicine.

Fig. 1.

Soft tissue showing nasal vestibule morphologies as described in Ramprasad and Frank-Ito (2016).⁽¹¹⁾.

Fig. 2.

Nasal airflow streamlines across nasal vestibule phenotypes (Standard—left panel, Elongated—middle panel, and Notched—right panel) at three flow rates (top row=10 L/min, middle row=30 L/min, and bottom row=50 L/min). Left and right columns within each phenotype represent two different subjects’ nasal passages.

Fig. 3.

LEFT: resistance values across nasal vestibule phenotypes (Standard=pink, Elongated=yellow, and Notched=black) at six increasing flow rates (10,15,20,30,40,and 50 L/min) measured from nostril to posterior end of the unilateral nasal vestibule (TOP LEFT) and the entire unilateral nasal cavity from nostril to choana (BOTTOM LEFT). RIGHT: average wall heat flux values across all nasal vestibule phenotypes (as above) at six increasing flow rates (as above). TOP RIGHT: shows values at the unilateral nasal vestibule region and BOTTOM RIGHT shows values for the entire unilateral nasal cavity.

Fig. 4.

Nasal wall heat flux color maps across nasal vestibule phenotypes (Standard—left panel, Elongated—middle panel, and Notched—right panel) at three flow rates (top row=10 L/min, middle row=30 L/min, and bottom row=50 L/min). Left and right columns within each phenotype represent two different subjects’ nasal passages from nostril to choana.