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Q1: Definition & approach (2 min)
"Define chronic cough and outline your initial approach in primary care."
- Chronic cough = cough lasting more than 8 weeks in an adult (acute less than 3 weeks, subacute 3 to 8 weeks, chronic more than 8 weeks).
- First: chest X-ray for ALL — exclude serious disease (lung cancer, TB, ILD, heart failure, bronchiectasis).
- Second: review smoking and the drug list — stop ACE inhibitors (replace with ARB); offer smoking cessation.
- Third: in a non-smoker with a normal CXR off ACE-i, treat the 'big three' causes sequentially and empirically — UACS, asthma/eosinophilic bronchitis, GORD.
- Only after failure of all of this is the cough termed refractory and managed at a specialist cough clinic.
Q2: The cough reflex and cough-reflex hypersensitivity (3 min)
"Walk me through the cough reflex arc and explain cough-reflex hypersensitivity."
- Afferents: vagal sensory fibres — Adelta rapidly-adapting receptors and unmyelinated C-fibres expressing TRPV1 (capsaicin/heat), TRPA1 (oxidants, cinnamaldehyde), TRPV4, and P2X3 (ATP-gated).
- Central: afferents synapse in the nucleus tractus solitarius (NTS) in the medulla; a cough pattern generator coordinates the motor sequence.
- Efferents: to the diaphragm, intercostals, laryngeal adductors (close glottis) and abdominal muscles — producing the inspiratory-compressive-expulsive phases.
- Cough-reflex hypersensitivity (CRH): peripheral sensitisation (inflammatory mediators — bradykinin, prostaglandins, neurotrophin NGF upregulate TRP channels) AND central sensitisation lower the cough threshold so innocuous stimuli (talking, cold air) trigger cough. This is the unifying mechanism of refractory/unexplained chronic cough.
- Each 'big three' cause drives CRH: UACS (mucus/mediants on pharyngeal receptors); eosinophilic disease (eosinophil mediators on C-fibres); GORD (vagally-mediated oesophageal-tracheobronchial reflex AND micro-aspiration of acid/pepsin/bile onto laryngeal mucosa).
Q3: Distinguishing the big three (3 min)
"At the bedside, how do you tell UACS, cough-variant asthma and GORD apart?"
- UACS (post-nasal drip) — nasal/sinus fullness, throat clearing, sensation of drip, worse in morning; often history of allergic rhinitis/sinusitis; trial of intranasal corticosteroid + antihistamine.
- Cough-variant asthma / eosinophilic bronchitis — dry nocturnal cough, atopy, triggered by cold air/exercise; cough-variant asthma ultimately shows bronchodilator reversibility (FEV1 at least 12 percent and 200 mL) or airway hyperresponsiveness; eosinophilic bronchitis has eosinophils in sputum (at least 3 percent) but NO obstruction/reversibility. FeNO 50 ppb or more supports both; trial of ICS.
- GORD — worse lying down/after meals, heartburn, regurgitation, hoarseness; often silent; trial of PPI + lifestyle for at least 8 weeks; pH/impedance if refractory.
Q4: Refractory cough and its complications (2 min)
"You have excluded all causes. What now — and what complications of chronic cough should you ask about?"
- Refractory chronic cough (RCC) — manage at a specialist cough clinic:
- Speech-language pathology / cough-suppression therapy (RCT-supported first-line).
- Neuromodulators — gabapentin up to 1800 mg/day (Ryan, Lancet 2012) or pregabalin 75 to 300 mg/day; low-dose slow-release morphine short course.
- P2X3 antagonist (gepapixant) where licensed.
- Avoid long-term codeine/dextromethorphan.
- Complications to ask about (the four classic + psychosocial): urinary incontinence (women), rib fractures (cough fractures), cough (tussive) syncope (raised intrathoracic pressure obstructs venous return), sleep disturbance, plus depression, social embarrassment, work loss.