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Upper airway pressure-flow relationships in obstructive sleep apnea
P L Smith1, R A Wise, A R Gold
1Department of Medicine, Francis Scott Key Medical Center, Johns Hopkins University School of Medicine, Baltimore, Maryland 21224.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|February 1, 1988
Summary
Obstructive sleep apnea patients exhibit Starling resistor behavior in their upper airways. Applying positive nasal pressure above a critical opening pressure (Pcrit) effectively increased airflow and resolved apneas.
Area of Science:
- Respiratory Physiology
- Sleep Medicine
- Biomedical Engineering
Background:
- Obstructive sleep apnea (OSA) involves upper airway collapse during sleep.
- Understanding the biomechanics of the upper airway is crucial for effective treatment.
Purpose of the Study:
- To investigate the pressure-flow dynamics in the upper airway of OSA patients.
- To determine if the upper airway functions as a Starling resistor.
Main Methods:
- Six OSA patients underwent polysomnography during non-rapid-eye-movement sleep.
- Incremental positive airway pressure was applied via a nasal mask.
- Critical opening pressure (Pcrit) and airflow were measured.
Main Results:
- A positive Pcrit of 3.3 ± 3.3 cmH2O was observed.
- Increasing nasal pressure above Pcrit proportionally increased inspiratory airflow, abolishing apneas.
- Full face mask application prevented airflow and Pcrit determination.
Conclusions:
- The upper airway in OSA patients functions as a Starling resistor.
- A collapsible segment in the oropharynx explains the observed pressure-flow relationships.
- This model unifies the understanding of sleep apnea, hypopnea, and snoring.