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Tracheal hysteresis in sleep apnea
1Department of Medicine, St. Michael's Hospital, Toronto, Ontario, Canada.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|October 1, 1989
Summary
Patients with obstructive sleep apnea have reduced upper airway muscle tone that extends into the trachea. This finding was determined by measuring tracheal area changes during breathing in apneic and nonapneic individuals.
Area of Science:
- Respiratory Physiology
- Sleep Medicine
- Otolaryngology
Background:
- Obstructive sleep apnea (OSA) is characterized by pharyngeal wall collapsibility, linked to reduced pharyngeal muscle tone.
- This muscle hypotonia may extend beyond the pharynx into the trachea, affecting airway stability.
Purpose of the Study:
- To investigate whether reduced upper airway muscle tone in obstructive sleep apnea patients extends into the trachea.
- To infer tracheal muscle tone by measuring tracheal area hysteresis relative to lung volume.
Main Methods:
- Relative hysteresis of the proximal and distal trachea was measured using acoustic reflection during wakefulness.
- Tracheal cross-sectional area was plotted against lung volume to assess hysteresis in 42 patients with OSA (apnea/hypopnea index > 10) and 33 nonapneic controls (apnea/hypopnea index ≤ 10).
Main Results:
- In patients with OSA, proximal tracheal hysteresis was predominantly clockwise (smaller than lung parenchyma), indicating reduced tone.
- In nonapneic individuals, proximal tracheal hysteresis was predominantly counter-clockwise (larger than lung parenchyma).
- Both groups exhibited similar, clockwise hysteresis in the distal trachea.
Conclusions:
- Reduced upper airway muscle tone in obstructive sleep apnea patients extends into the proximal trachea.
- Tracheal hysteresis measurement is a viable method for inferring tracheal muscle tone in vivo.