Effects of decongestion on nasal cavity air conditioning efficiency: a CFD cohort study

Abstract

Decongestion reduces blood flow in the nasal turbinates, enlarging the airway lumen. Although the enlarged airspace reduces the trans-nasal inspiratory pressure drop, symptoms of nasal obstruction may relate to nasal cavity air-conditioning. Thus, it is necessity to quantify how efficient nasal cavity conditioning the inhaled air. This study quantifies both overall and regional nasal air-conditioning in a cohort of 10 healthy subjects using computational fluid dynamics simulations before and after nasal decongestion. The 3D virtual geometry model was segmented from magnet resonance images (MRI). Each subject was under two MRI acquisitions before and after decongestion condition. The effects of decongestion on nasal cavity air conditioning efficiency were modelled at two inspiratory flowrates: 15 and 30 \(L.mi{n}^{-1}\) to represent restful and light exercise conditions. Results show inhaled air was both heated and humidified up to 90% of alveolar conditions at the posterior septum. The air-conditioning efficiency of the nasal cavity remained nearly constant between nostril and posterior septum but dropped significantly after posterior septum. In summary, decongestion not only reduce nasal cavity added heat by 23% and added moisture content by 19% to inhaled air, but also reduce the air-conditioning efficiency by 35% on average.