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Laryngeal constriction in normal humans during experimentally induced bronchoconstriction
Journal of Applied Physiology (Bethesda, Md. : 1985)
|February 1, 1985
Summary
Bronchoconstriction narrows the glottis during normal breathing, increasing airway resistance. This paradoxical laryngeal response may help maintain lung volume during asthma attacks.
Area of Science:
- Respiratory Physiology
- Pulmonary Medicine
- Laryngeal Function
Background:
- Bronchoconstriction, a hallmark of asthma, involves narrowing of the airways.
- The role of the glottis, the adjustable opening between the vocal cords, in bronchoconstriction is not fully understood.
- Understanding laryngeal responses is crucial for comprehending overall airway dynamics during respiratory challenges.
Purpose of the Study:
- To investigate changes in glottic size during experimentally induced bronchoconstriction.
- To assess the impact of bronchoconstriction on laryngeal resistance during different breathing patterns.
Main Methods:
- Six healthy subjects inhaled histamine or methacholine to induce bronchoconstriction.
- Glottic size was measured during tidal breathing and panting (2-3 Hz).
- Measurements were taken during both inspiration and expiration.
Main Results:
- A mean 8% decrease in mid-expiratory glottic size was observed during bronchoconstriction compared to control during tidal breathing.
- Changes in mid-inspiratory glottic size were inconsistent.
- During panting, glottic size remained stable between inspiration and expiration, but decreased in 7 of 15 studies during bronchoconstriction.
Conclusions:
- Bronchoconstriction leads to a decrease in expiratory glottic size, increasing laryngeal resistance.
- This paradoxical laryngeal response, coupled with increased lower airway resistance, may contribute to hyperinflation.
- Maintaining hyperinflation could serve to enlarge the lower airways, potentially mitigating the effects of bronchoconstriction.