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Cited by 39Obstructive Sleep Apnea ResearchNasal Surgery and Airway StudiesRespiratory Support and Mechanisms

The DOI matches its Crossref record; 16 of the 16 references it cites were found in a registry or an index.

Effect of Nasal Obstruction on Continuous Positive Airway Pressure Treatment: Computational Fluid Dynamics Analyses

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Wakayama, Tadashi, Suzuki, Masaaki, Tanuma, Tadashi·2016·PLOS ONE
DOI 10.1371/journal.pone.0150951PMC PMC4778797
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Abstract

OBJECTIVE: Nasal obstruction is a common problem in continuous positive airway pressure (CPAP) therapy for obstructive sleep apnea and limits treatment compliance. The purpose of this study is to model the effects of nasal obstruction on airflow parameters under CPAP using computational fluid dynamics (CFD), and to clarify quantitatively the relation between airflow velocity and pressure loss coefficient in subjects with and without nasal obstruction. METHODS: We conducted an observational cross-sectional study of 16 Japanese adult subjects, of whom 9 had nasal obstruction and 7 did not (control group). Three-dimensional reconstructed models of the nasal cavity and nasopharynx with a CPAP mask fitted to the nostrils were created from each subject's CT scans. The digital models were meshed with tetrahedral cells and stereolithography formats were created. CPAP airflow simulations were conducted using CFD software. Airflow streamlines and velocity contours in the nasal cavities and nasopharynx were compared between groups. Simulation models were confirmed to agree with actual measurements of nasal flow rate and with pressure and flow rate in the CPAP machine. RESULTS: Under 10 cmH2O CPAP, average maximum airflow velocity during inspiration was 17.6 ± 5.6 m/s in the nasal obstruction group but only 11.8 ± 1.4 m/s in the control group. The average pressure drop in the nasopharynx relative to inlet static pressure was 2.44 ± 1.41 cmH2O in the nasal obstruction group but only 1.17 ± 0.29 cmH2O in the control group. The nasal obstruction and control groups were clearly separated by a velocity threshold of 13.5 m/s, and pressure loss coefficient threshold of approximately 10.0. In contrast, there was no significant difference in expiratory pressure in the nasopharynx between the groups. CONCLUSION: This is the first CFD analysis of the effect of nasal obstruction on CPAP treatment. A strong correlation between the inspiratory pressure loss coefficient and maximum airflow velocity was found.

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Figures

Fig 1 STL model of a nasal cavity and nasopharynx.
Fig 1 STL model of a nasal cavity and nasopharynx.CC BY · PubMed Central
Fig 2 Digital unstructured grid models.
Fig 2 Digital unstructured grid models.CC BY · PubMed Central
Fig 3 CFD computational domain of the nasal cavity, the nasopharynx, and a box-shaped closed space in front of the nostrils.
Fig 3 CFD computational domain of the nasal cavity, the nasopharynx, and a box-shaped closed space in front of the nostrils.CC BY · PubMed Central
Fig 4 Airflow and velocity distributions in the nasal cavity and nasopharynx under 10 cmH2O CPAP (left panel). Velocity distributions in the nasal cavity and nasopharynx (right panel). Velocity contour mappings are shown in a colored distribution. Red streamlines indicate high velocity, and blue streamlines indicate low velocity, implying impaired airflow. Inspiratory airflow on the narrowed side became a rapid stream, as fast as 32.7 m/s. In contrast, the velocity on the normal side was 7.6 m/s. Airflow was not able to disperse across the entire cross-sectional area and thus became a concentrated, rapidly moving stream. Turbulence in front of the nostrils was seen. X-axis: distance from the nostrils; Y-axis: velocity (V, m/s) (right panel).
Fig 4 Airflow and velocity distributions in the nasal cavity and nasopharynx under 10 cmH2O CPAP (left panel). Velocity distributions in the nasal cavity and nasopharynx (right panel). Velocity contour mappings are shown in a colored distribution. Red streamlines indicate high velocity, and blue streamlines indicate low velocity, implying impaired airflow. Inspiratory airflow on the narrowed side became a rapid stream, as fast as 32.7 m/s. In contrast, the velocity on the normal side was 7.6 m/s. Airflow was not able to disperse across the entire cross-sectional area and thus became a concentrated, rapidly moving stream. Turbulence in front of the nostrils was seen. X-axis: distance from the nostrils; Y-axis: velocity (V, m/s) (right panel).CC BY · PubMed Central
Fig 5 Caudal views comparing airflow and velocity contours with CPAP. Same patient as Fig 4.
Fig 5 Caudal views comparing airflow and velocity contours with CPAP. Same patient as Fig 4.CC BY · PubMed Central
Fig 6 Inspiratory static pressure distribution (10 cmH2O, 889 ml/s). The pressure drop was 102460 − 101935 = 525 Pa = 5.35 cmH2O. Same patient as Fig 4.
Fig 6 Inspiratory static pressure distribution (10 cmH2O, 889 ml/s). The pressure drop was 102460 − 101935 = 525 Pa = 5.35 cmH2O. Same patient as Fig 4.CC BY · PubMed Central
Fig 7 Scatter plot of maximum velocity versus inspiratory pressure loss coefficient (Cp). The nasal obstruction and control groups were separated by a velocity threshold of 13.5 m/s and Cp threshold of approximately 10.0. r = 0.776, p<0.001. Blue squares: patients with nasal obstruction; red squares: controls.
Fig 7 Scatter plot of maximum velocity versus inspiratory pressure loss coefficient (Cp). The nasal obstruction and control groups were separated by a velocity threshold of 13.5 m/s and Cp threshold of approximately 10.0. r = 0.776, p<0.001. Blue squares: patients with nasal obstruction; red squares: controls.CC BY · PubMed Central
Fig 8 Scatter plot of relative cross-sectional area at the nostril versus inspiratory pressure loss coefficient (Cp). Note that the Cp thresholds were independent of the cross-sectional area at the nostrils. The longitudinal axis is the same Cp as Fig 7.
Fig 8 Scatter plot of relative cross-sectional area at the nostril versus inspiratory pressure loss coefficient (Cp). Note that the Cp thresholds were independent of the cross-sectional area at the nostrils. The longitudinal axis is the same Cp as Fig 7.CC BY · PubMed Central

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Metadata

Authors
Wakayama, T., Suzuki, M., & Tanuma, T.
Affiliations
  • Teikyo University (JP)
  • Teikyo University Chiba Medical Center (JP)
Corresponding author
  • Wakayama, Tadashi
  • Suzuki, Masaaki
  • Tanuma, Tadashi
ORCID
Suzuki, Masaaki
Venue
PLOS ONE
Publisher
Public Library of Science (PLoS)
Published
2016-03-04
Volume
11
Issue
3
Pages
e0150951
ISSN
1932-6203 (ISSN-L)
DOI
10.1371/journal.pone.0150951
PMC
PMC4778797
OpenAlex
W2294451322
Cited by
39
References
16
Citations by year
2026: 5 · 2025: 2 · 2024: 6 · 2023: 3 · 2022: 1 · 2021: 11 · 2020: 5 · 2019: 2 · 2018: 2 · 2017: 1 · 2016: 1
FWCI
1.61
Type
journal article
Language
en
Open access
Licence
Locations
  • PLoS ONE (publishedVersion, cc-by)
  • Europe PMC (PubMed Central) (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • Institutional Repositories DataBase (IRDB) (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • Institutional Repositories DataBase (IRDB) (submittedVersion, cc-by)
Topics
  • Health Sciences › Medicine › Physiology (medical) › Obstructive Sleep Apnea Research
  • Health Sciences › Medicine › Surgery › Nasal Surgery and Airway Studies
  • Health Sciences › Medicine › Pulmonary and Respiratory Medicine › Respiratory Support and Mechanisms
Keywords
nasal obstruction, continuous positive airway pressure, obstructive sleep apnea, pressure loss coefficient, CPAP masks
MeSH terms
Adult, Aged, Humans, Middle Aged, Nasal Cavity, Nasopharynx, Radiographic Image Interpretation, Computer-Assisted, Pulmonary Ventilation, Tomography, X-Ray Computed, Nasal Obstruction, Continuous Positive Airway Pressure, Hydrodynamics

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