Effects of respiratory rate on the fluid mechanics of a reconstructed upper airway. (February 2022)

• Record Type: Journal Article
• Authors: Burchell, Christopher; Kourmatzis, Agisilaos; Zhao, Yongling; Raco, Joel; Mekonnen, Taye; Chan, Hak-Kim; Cheng, Shaokoon
• Is Part Of: Medical engineering & physics. Volume 100(2022)
• Publication Date: 2022-02
• Subjects: Particle image velocimetry -- Extra-thoracic -- Airways -- Epiglottis -- Tidal breathing -- Respiratory rate -- Breathing frequency -- MRI reconstructed upper airway model -- Deformable airway -- MRI -- Rigid model -- Active deformation -- Patency -- Flow homogeny -- Womersley -- Reynolds -- Inspiratory -- Expiratory -- Pulsatile -- Fllow Field; Biomedical engineering -- Periodicals; Biomedical Engineering -- Periodicals; Physics -- Periodicals; Génie biomédical -- Périodiques; Biomedical engineering; Electronic journals; Periodicals; 610.28
• DOI: 10.1016/j.medengphy.2021.103746
• Languages: English
• ISSNs: 1350-4533

Abstract

Highlights: Investigating the effects of respiratory rate on the upper airway. Implications of the use of rigid versus an actively deformed upper airway model. Respiratory rate had the greatest influence at the onset of inspiration/expiration. Airway collapse at the level of the soft palate homogenised downstream flow. Actively deforming models showed greater adhesion of flow to the tongue. Abstract: This study aims to utilise particle image velocimetry (PIV) techniques to investigate the time-dependant effects of respiratory rate in the extrathoracic airway, to show how they affect the flow field developed. There has been limited validation of computational fluid dynamics (CFD) models using experimental setups. Furthermore, the large majority of existing CFD models focus on rigid airways, not accounting for active deformation through the breathing cycle. Experiments were carried out to expand upon Zhao et al.'s previous study, in which a single respiratory rate was investigated. This studied utilised a transient, sinusoidal flow profile with two respiratory rates of 10 breaths per minute (BPM) and 25 BPM, both achieving a maximum flow rate correlating to 5 L/min in air to simulate tidal breathing. Results from this study showed that respiratory rate had the greatest influence near the onset of the inspiratory and expiratory manoeuvres, with the higher respiratory rate homogenising later in the cycle. It was shown that airway deformation at the level of the soft palate homogenised flow downstream of the deformation which resulted in a lower peak magnitude velocity for approximately 40% of the cycle at the level of the epiglottis, when compared to the rigid airway model.