Cough

Medicine > Cardiovascular

Differential Diagnosis Schema 🧠

Infectious Causes

Upper respiratory tract infection (URTI): Common cause, often viral, associated with sore throat, rhinorrhoea, and mild fever.
Acute bronchitis: Productive cough, often following a viral infection, may have wheeze or chest discomfort.
Pneumonia: Cough with purulent sputum, fever, pleuritic chest pain, and dyspnoea, often with signs of consolidation on examination.
Tuberculosis: Chronic cough, often with haemoptysis, night sweats, weight loss, and risk factors like exposure or immunocompromise.
Pertussis (whooping cough): Paroxysmal cough with inspiratory “whoop”, often in unvaccinated children or waning immunity in adults.

Chronic Respiratory Conditions

Asthma: Episodic cough, wheezing, shortness of breath, often worse at night or with triggers such as allergens or exercise.
Chronic obstructive pulmonary disease (COPD): Chronic productive cough, dyspnea, history of smoking, frequent winter exacerbations.
Bronchiectasis: Persistent cough with copious sputum production, recurrent chest infections, often with history of childhood respiratory illnesses.
Interstitial lung disease (ILD): Dry cough, progressive dyspnea, often with a history of occupational exposure, connective tissue disease, or medications.
Cystic fibrosis: Chronic cough with thick, purulent sputum, recurrent chest infections, often diagnosed in childhood.

Cardiovascular Causes

Heart failure: Chronic cough, often worse when lying flat, associated with orthopnoea, paroxysmal nocturnal dyspnea, and peripheral oedema.
Pulmonary embolism: Sudden onset cough, dyspnea, pleuritic chest pain, haemoptysis, often with risk factors like recent surgery, immobility, or malignancy.
Left ventricular dysfunction: Cough due to pulmonary congestion, often associated with exertional dyspnea and fatigue.
Mitral stenosis: Chronic cough, haemoptysis, atrial fibrillation, signs of heart failure, often due to rheumatic heart disease.
Aortic aneurysm: Cough due to compression of the trachea or recurrent laryngeal nerve, associated with hoarseness and dysphagia.

Gastrointestinal Causes

Gastroesophageal reflux disease (GORD): Chronic cough, often worse at night or after meals, associated with heartburn, regurgitation, and sour taste.
Aspiration: Chronic cough, often in patients with dysphagia, neurological disorders, or oesophageal motility disorders, associated with recurrent chest infections.
Tracheoesophageal fistula: Congenital or acquired abnormal connection between the trachea and oesophagus, presenting with cough, choking on feeds, and recurrent respiratory infections.
Hiatal hernia: May cause GORD symptoms leading to cough, often associated with postprandial fullness and discomfort.
Oesophageal motility disorders: Dysphagia, regurgitation, and cough, often worse with certain foods or liquids.

Other Causes

Medications (e.g., ACE inhibitors): Persistent dry cough, often resolving after discontinuation of the offending drug.
Psychogenic cough: Chronic, habit cough, often in the absence of underlying disease, more common in children and adolescents.
Foreign body aspiration: Sudden onset cough, often in children, associated with choking episodes and possible unilateral wheeze or decreased breath sounds.
Occupational exposure: Chronic cough in individuals exposed to dust, fumes, or chemicals, often associated with a history of workplace exposure.
Lung cancer: Persistent cough, often with haemoptysis, unexplained weight loss, and risk factors like smoking or asbestos exposure.
Interstitial lung disease: Persistent dry cough with dyspnoea, often in the context of connective tissue disease, occupational exposure, or idiopathic.

Key Points in History 🥼

Onset and Duration

Acute vs chronic: Acute cough is often infectious (e.g., URTI, pneumonia), while chronic cough (>8 weeks) suggests chronic respiratory or other systemic conditions.
Triggers: Identify any environmental, occupational, or allergenic triggers that may exacerbate cough (e.g., cold air, exercise, exposure to dust or smoke).
Diurnal variation: Cough that worsens at night suggests asthma, GORD, or heart failure, while cough that worsens in the morning suggests COPD or bronchiectasis.
Associated symptoms: Presence of sputum, haemoptysis, wheeze, chest pain, fever, or dyspnoea can help narrow the differential diagnosis.
Recent illness or infection: History of recent respiratory infection may suggest post-infectious cough or acute bronchitis.

Background

Past medical history: Review history of asthma, COPD, heart failure, GORD, or recent infections, as these conditions can all cause chronic cough.
Drug history: Consider medications known to cause cough, such as ACE inhibitors, and review recent changes in medication.
Family history: Consider family history of atopy (asthma, eczema, hay fever), cystic fibrosis, or lung cancer, which may increase the risk of certain conditions.
Social history: Smoking status, occupational exposure to dusts or chemicals, and alcohol use, which can all contribute to or exacerbate cough.
Travel history: Recent travel, particularly to areas endemic with TB, may suggest a higher risk of tuberculosis or other respiratory infections.
Allergy history: Identify any known allergens or history of atopy, which can suggest a diagnosis of asthma or allergic rhinitis.
Environmental exposure: Consider exposure to pets, mold, or other environmental factors that may trigger or worsen a cough.
Immunisation history: Particularly for pertussis, influenza, and pneumococcal vaccines, which can influence susceptibility to certain infections.

Possible Investigations 🌡️

Bedside Tests

Pulse oximetry: To assess oxygen saturation, particularly in acute settings or if respiratory compromise is suspected.
Peak flow measurement: Useful in assessing for asthma or COPD, with variability suggesting asthma.
Sputum analysis: If productive cough, culture and sensitivity testing can help identify causative organisms, particularly in cases of pneumonia or tuberculosis.
ECG: To rule out cardiac causes of cough, particularly if heart failure or pulmonary embolism is suspected.
Spirometry: To assess lung function, particularly in suspected asthma, COPD, or interstitial lung disease.

Blood Tests

Full blood count: To assess for infection (leukocytosis) or anaemia (which may exacerbate symptoms of heart failure).
C-reactive protein (CRP): To assess for inflammation or infection, particularly if pneumonia or another inflammatory condition is suspected.
Arterial blood gases (ABG): To assess for respiratory acidosis or hypoxaemia in cases of severe respiratory distress or COPD exacerbation.
Brain natriuretic peptide (BNP): Elevated in heart failure, useful in differentiating between cardiac and pulmonary causes of cough.
Immunoglobulin E (IgE): Elevated in allergic conditions and asthma, may help in confirming atopy.
Mycobacterial culture: If tuberculosis is suspected, to confirm diagnosis through sputum analysis or bronchoalveolar lavage.

Imaging and Special Tests

Chest X-ray: First-line imaging to assess for pneumonia, lung cancer, tuberculosis, or heart failure.
CT scan of the chest: Provides detailed imaging for suspected malignancy, interstitial lung disease, or pulmonary embolism.
Bronchoscopy: Useful for visualising the airways, obtaining biopsies, or removing foreign bodies, particularly in cases of unexplained cough or haemoptysis.
Echocardiography: To assess cardiac function, particularly in suspected heart failure or pulmonary hypertension.
Barium swallow: To assess for GORD or oesophageal motility disorders if these are suspected causes of chronic cough.
Allergy testing: Skin prick testing or specific IgE testing may be indicated if allergic asthma or rhinitis is suspected.
24-hour pH monitoring: To confirm GORD as a cause of chronic cough, particularly if the diagnosis is unclear.

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Cough

Differential Diagnosis Schema 🧠

Key Points in History 🥼

Possible Investigations 🌡️

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Cardiovascular