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The expiration reflex from the vocal folds
1Department of Pathophysiology, Jessenius Medical School, Comenius University, Martin, Slovakia.
Acta Physiologica Hungarica
|June 29, 2001
Summary
The expiration reflex, distinct from cough, protects airways from foreign bodies. This reflex, elicited via the superior laryngeal nerve, involves a forceful expiration without prior inspiration.
Area of Science:
- Respiratory Physiology
- Neuroscience
Background:
- The expiration reflex is a protective mechanism involving the vocal folds.
- Unlike cough, it lacks a preceding inspiration, preventing potential aspiration pneumonia.
- Also known as "laryngeal cough," its receptors are stable in pathological conditions.
Purpose of the Study:
- To detail 30 years of experience with the expiration reflex.
- To elucidate the reflex's mechanism, neural control, and physiological role.
Main Methods:
- Elicitation of the reflex through mechanical, chemical, or electrical stimulation of the superior laryngeal nerve in humans and animals (excluding mice and rats).
- Review of existing literature and clinical experience regarding the reflex's characteristics and neural pathways.
Main Results:
- The expiration reflex is triggered by superior laryngeal nerve stimulation, resulting in a rapid, forceful expiration.
- Its primary function is to prevent foreign body aspiration and clear the subglottal area.
- Receptor localization in the vocal fold mucosa suggests resilience to laryngeal pathologies.
- Neural coordination involves a brainstem network, including the Botzinger complex and rostral ventral respiratory group, with potential contributions from other brainstem areas.
Conclusions:
- The expiration reflex is a crucial, non-inspiratory airway defense mechanism.
- Its unique characteristics and neural network highlight its specialized role in respiratory protection.
- Understanding this reflex is vital for laryngologists and respiratory physiologists.