Noninvasive estimation of pharyngeal airway resistance and compliance in children based on volume-gated dynamic MRI and computational fluid dynamics

Steven C. Persak, Sanghun Sin, Joseph M. McDonough, Raanan Arens, David M. Wootton

Research output: Contribution to journalArticle

28 Scopus citations

Abstract

Computational fluid dynamics (CFD) analysis was used to model the effect of collapsing airway geometry on internal pressure and velocity in the pharyngeal airway of three sedated children with obstructive sleep apnea syndrome (OSAS) and three control subjects. Model geometry was reconstructed from volume-gated magnetic resonance images during normal tidal breathing at 10 increments of tidal volume through the respiratory cycle. Each geometry was meshed with an unstructured grid and solved using a low-Reynolds number k-ω turbulence model driven by flow data averaged over 12 consecutive breathing cycles. Combining gated imaging with CFD modeling created a dynamic three-dimensional view of airway anatomy and mechanics, including the evolution of airway collapse and flow resistance and estimates of the local effective compliance. The upper airways of subjects with OSAS were generally much more compliant during tidal breathing. Compliance curves (pressure vs. cross-section area), derived for different locations along the airway, quantified local differences along the pharynx and between OSAS subjects. In one subject, the distal oropharynx was more compliant than the nasopharynx (1.028 vs. 0.450 mm 2/Pa) and had a lower theoretical limiting flow rate, confirming the distal oropharynx as the flow-limiting segment of the airway in this subject. Another subject had a more compliant nasopharynx (0.053 mm 2/Pa) during inspiration and apparent stiffening of the distal oropharynx (C = 0.0058 mm2/Pa), and the theoretical limiting flow rate indicated the nasopharynx as the flowlimiting segment. This new method may help to differentiate anatomical and functional factors in airway collapse.

Original languageEnglish (US)
Pages (from-to)1819-1827
Number of pages9
JournalJournal of applied physiology
Volume111
Issue number6
DOIs
StatePublished - Dec 1 2011

Keywords

  • Airway resistance
  • CFD
  • Flow limitation
  • Human
  • Obstructive sleep apnea

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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