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Related Experiment Videos

Progressive retropalatal narrowing preceding obstructive apnea

M J Morrell1, Y Arabi, B Zahn

  • 1William S. Middleton Memorial Veterans Hospital, Department of Preventive Medicine, University of Wisconsin Medical School, Madison, Wisconsin, USA.

American Journal of Respiratory and Critical Care Medicine
|December 16, 1998
PubMed
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Obstructive sleep apnea airway narrowing occurs during exhalation, not just inhalation. This expiratory narrowing significantly reduces pharyngeal cross-sectional area before an obstructive event.

Area of Science:

  • Sleep Medicine
  • Respiratory Physiology
  • Otolaryngology

Background:

  • Obstructive apnea is typically viewed as an inspiratory event.
  • However, pharyngeal occlusion can occur without negative intrathoracic pressure.

Purpose of the Study:

  • To investigate the hypothesis that inspiratory-related pharyngeal occlusion is preceded by significant expiratory airway narrowing.

Main Methods:

  • Studied eight sleeping patients with obstructive apnea.
  • Monitored pharyngeal caliber, airflow, and esophageal pressure (Pes) during breaths preceding occlusion.
  • Measured retropalatal airway cross-sectional area (CSA) using fiberoptic images.

Main Results:

  • Inspiratory CSA reduction was significant only during the breath immediately before apnea.

Related Experiment Videos

  • During expiration, pharyngeal CSA initially increased then significantly narrowed at end-expiration.
  • Airway occlusion occurred at a lower Pes than during the preceding unoccluded breath.

    • Conclusions:

    • Expiratory narrowing significantly reduces pharyngeal cross-sectional area before obstructive apnea.
    • This finding challenges the view of apnea as solely an inspiratory event.