Chronic Cough: Pathogenesis
ACE Inhibitors
Protussive mediator accumulation (bradykinin, substance P)
Infection
IP; likely chronic ↑ cough receptors commonly pertussis- related or post-viral
Asthma
↑ EDN
↑ MBP levels in RT
Neoplasm
Bronchiectasis
COPD
GERD
Allergic Rhinitis
↑ sputum production
and accumulation
Damage from chronic inflammation causes poor mucus clearance
Inhalants trigger ↑ cytokines ↑ mucus
Aspiration of refluxed microdroplets
Irritation by post- nasal drip
↑ inflammatory mediators in RT
Mechanical obstructions (i.e. mediastinal masses, neoplasms)
Foreign body Presence irritation of irritants
Stimulation of sensory nerve receptors expressed on nerve endings penetrating the epithelia of the upper RT
Abbreviations:
• RT: respiratory tract
• IP: indefinite
pathophysiology
• GERD: Gastro-esophageal
reflux disease
• EDN: Eosinophil-derived
neurotoxin
• MBP: Major basic protein
• COPD: Chronic
Obstructive Pulmonary Disease
Complications: Syncope, insomnia, hemoptysis, rib fractures
Slowly adapting receptors
Respond to mechanical forces during breathing
Stimulation of the vagus nerve
Activation of nucleus tractus solitarius in central respiratory generator (brainstem)
Generation of efferent cough signal
Chronic cough: Cough of over 8 weeks duration with no dyspnea or fever
C-fibre receptors
Respond to chemical stimuli (bradykinin, capsaicin, acid/alkaline solutions, mannitol, hypertonic saline, and other inhaled irritants)
Authors: Arsalan Ahmad Lance Bartel Reviewers: Midas (Kening) Kang Usama Malik Ciara Hanly Yonglin Mai (麦泳琳) Yan Yu*, Eric Leung* * MD at time of publication
Rapidly adapting receptors
Responds to mechanical stimuli, such as physical obstruction of the airways
Legend:
Pathophysiology
Mechanism
Sign/Symptom/Lab Finding
Complications
Published Feb 06, 2018, updated Dec 4, 2021 on www.thecalgaryguide.com