The applied physiology of cough

Area of Science:

• Respiratory Physiology
• Clinical Medicine
• Defense Mechanisms

Background:

• The cough reflex is a critical defense mechanism for the respiratory tract.
• Its applied physiology is essential knowledge for clinicians managing respiratory diseases.
• The reflex involves afferent and efferent limbs, with a central cough center in the brainstem.

Purpose of the Study:

• To elucidate the applied physiology of the cough reflex in the context of respiratory disease.
• To detail the mechanisms underlying the cough reflex and its role in maintaining airway clearance.
• To discuss the pathophysiological basis of various cough types encountered in clinical practice.

Main Methods:

• Description of the cough reflex's integrated structure: afferent limb (receptors, nerves), central cough center, and efferent limb (motor nerves, muscles).
• Explanation of the three phases of the cough process: inspiratory, compressive, and expiratory.
• Discussion of stimuli initiating the cough reflex (central, peripheral, pulmonary, extrapulmonary).

Main Results:

• The cough reflex maintains airway and alveolar health through high-velocity expiratory gas flows and positive pleural pressure-induced lung compression.
• Cough threshold can be quantified using inhalation challenge tests with agents like acetic acid, citric acid, or capsaicin.
• These methods have practical applications in clinical research for assessing cough sensitivity.

Conclusions:

• A comprehensive understanding of cough reflex physiology is fundamental for clinical practice, particularly in respiratory diseases.
• The mechanisms of airway clearance via cough are effective due to specific phases and pressure dynamics.
• Quantifying cough threshold offers valuable insights for clinical research and patient management.