Local deposition fractions of ultrafine particles in a human nasal-sinus cavity CFD model

Abstract

Ultrafine particle deposition studies in the human nasal cavity regions often omit the paranasal sinus regions. Because of the highly diffusive nature of nanoparticles, it is conjectured that deposition by diffusion may occur in the paranasal sinuses, which may affect the residual deposition fraction that leaves the nasal cavity. Two identical CFD models of a human nasal cavity, one with sinuses and one without, were reconstructed from CT-scans to determine the uptake of ultrafine particles. In general, there was little flow passing through the paranasal sinuses. However, flow patterns revealed that some streamlines reached the upper nasal cavity near the olfactory regions. These flow paths promote particle deposition in the sphenoid and ethmoid sinuses. It was found that there were some differences in the deposition fractions and patterns for 5 and 10 nm particles between the nasal-sinus and the nasal cavity models. This difference is amplified when the flow rate is decreased and at a flow rate of 4 L/min the maximum difference was 17%. It is suggested that evaluations of nanoparticle deposition should consider some deposition occurring in the paranasal sinuses especially if flow rates are of concern.

Detailed micro-particle deposition patterns in the human nasal cavity influenced by the breathing zone

“…Pressure drop against flow rates (from 0 to 15 L/min) compared with reported data from Kelly et al[50], Schroeter et al[51], Wen et al[7], and Ge et al[40].…”

“…Further step-like surface regions were improved and smoothed using the 3D modelling software Geomagic Studio. For simplicity, openings to sinuses were omitted as their impact to air flow pattern and micron particle deposition were negligible [40]. The facial details were retained while the back of the head was omitted.…”

Numerical simulation of pharyngeal airflow applied to obstructive sleep apnea: effect of the nasal cavity in anatomically accurate airway models

“…The steady flow simulations carried out with two subjects show that the inclusion/exclusion of the frontal, ethmoidal, sphenoidal and maxillary sinuses in the airway model has repercussions on the flow properties in the nasal cavity upstream of the pharynx. As observed by [11], these modifications of the flow predictions can be important when particle deposition in the nasal cavity is considered. However, the influence of the different sinuses on the nasal resistance [38] and on the flow conditions downstream of the nasal cavity remains limited.…”

“…Investigations including flow simulations in idealized geometries [10], as well as in-vitro measurements, visualization and numerical simulations in realistic geometries [7,9,20,21,32], have shown the complexity of the flow patterns within the nasal airway and the variability of flow features between individuals [32]. Most of these studies have been aimed at quantitative characterizations of the nasal airflow necessary to analyze nasal abnormalities [6] and particle deposition [11]. Regarding OSA, while nasal obstruction has been recognized as a risk factor [22], it is generally accepted that for most patients with OSA, the nasal cavity is healthy and soft-tissue collapse occurs during inspiration in the pharynx [8,30,33].…”

Consideration of the respiratory cycle asymmetry in the numerical modeling of the submicron particles deposition in the human nasal cavity

“…In this figure, three curves reflect the results obtained for [4][5][6], the remaining four represent calculations for different original models. In four papers [4][5][6][7], the Euler approach was used to calculate particle motion, the others [8,9] and our work used the Lagrange approach. Following the authors of [4], we can recognize the comparison as quite good.…”