Airflow limitation in a collapsible model of the human pharynx: physical mechanisms studied with fluid-structure interaction simulations and experiments.
Physiol Rep
; 7(10): e14099, 2019 05.
Article
in En
| MEDLINE
| ID: mdl-31116516
ABSTRACT
The classical Starling Resistor model has been the paradigm of airway collapse in obstructive sleep apnea (OSA) for the last 30 years. Its theoretical framework is grounded on the wave-speed flow limitation (WSFL) theory. Recent observations of negative effort dependence in OSA patients violate the predictions of the WSFL theory. Fluid-structure interaction (FSI) simulations are emerging as a technique to quantify how the biomechanical properties of the upper airway determine the shape of the pressure-flow curve. This study aimed to test two predictions of the WSFL theory, namely (1) the pressure profile upstream from the choke point becomes independent of downstream pressure during flow limitation and (2) the maximum flowrate in a collapsible tube is VImax=A3/2(ρdA/dP)-1/2 , where ρ is air density and A and P are the cross-sectional area and pressure at the choke point respectively. FSI simulations were performed in a model of the human upper airway with a collapsible pharynx whose wall thickness varied from 2 to 8 mm and modulus of elasticity ranged from 2 to 30 kPa. Experimental measurements in an airway replica with a silicone pharynx validated the numerical methods. Good agreement was found between our FSI simulations and the WSFL theory. Other key findings include (1) the pressure-flow curve is independent of breathing effort (downstream pressure vs. time profile); (2) the shape of the pressure-flow curve reflects the airway biomechanical properties, so that VImax is a surrogate measure of pharyngeal compliance.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Pharynx
/
Respiration
/
Computer Simulation
/
Sleep Apnea, Obstructive
/
Airway Obstruction
/
Models, Anatomic
/
Models, Biological
Type of study:
Prognostic_studies
Limits:
Female
/
Humans
/
Middle aged
Language:
En
Journal:
Physiol Rep
Year:
2019
Document type:
Article