Understanding Asthma: Symptoms and Diagnosis

Asthma

• A chronic inflammatory disorder affecting the airways, involving various cells and cellular elements.
• Chronic inflammation results in airway hyper-responsiveness.
• Recurrent episodes include wheezing, breathlessness, chest tightness, and coughing, especially at night and early morning.
• Airflow obstruction within the lung is widespread but variable.
• Airflow obstruction is often reversible, either spontaneously or with treatment.

Clinical Features of Asthma

• Typical symptoms: recurrent wheezing, chest tightness, breathlessness, and cough.
• Asthma is commonly mistaken for a cold or persistent chest infection lasting over 10 days.
• Classical triggers include: exercise, cold weather, airborne allergens/pollutants, and viral upper respiratory infections.
• Prescription drugs can trigger asthma, including beta-adrenoceptor antagonists (β-blockers), even in topical forms like eye drops.
• Bronchospasm can be induced by aspirin and other NSAIDs.

Diagnosis of Asthma

• Predominantly clinical, based on a combination of history, lung function, and other tests.
• These can indicate high, intermediate, or low probability of asthma.
• The approach might need re-evaluation after treatment begins and can vary from patient to patient.
• Variable airflow obstruction is demonstrated using spirometry to measure FEV1 and FVC (forced vital capacity).
• Spirometry identifies the obstructive defect and its severity, providing a baseline for bronchodilator reversibility.
• Diagnosis can be supported by peripheral blood eosinophilia or atopy, shown in skin-prick tests, or measuring total and allergen-specific IgE.
• X-ray appearances are often normal, but lobar collapse may be seen if mucus blocks a large bronchus.
• Flitting infiltrates suggest a complication from allergic bronchopulmonary aspergillosis.

Diagnosing Asthma

• Requires a compatible clinical history along with one or more of the criteria.
• An increase of FEV1 ≥12% (and 200 mL) occurs after bronchodilator or glucocorticoid administration.
• Confidence is increased if the FEV1 increase is >15% and >400 mL.
• Diurnal variation >20% on ≥3 days in a week, monitored for 2 weeks via PEF diary.
• FEV1 shows ≥15% decrease after 6 minutes of exercise.
• FEV1 is the forced expiratory volume in 1 second and PEF is the peak expiratory flow.

Managing Asthma

• Avoid aggravating factors.
• Use stepwise management.

Chronic Obstructive Pulmonary Disease (COPD)

• COPD is defined as a preventable and treatable disease characterized by persistent respiratory symptoms.
• COPD is characterized by airflow limitation from airway and/or alveolar abnormalities which are usually caused by significant exposure to noxious particles or gases.
• The spectrum of COPD includes chronic bronchitis and emphysema.
• Chronic bronchitis is defined as cough and sputum for at least 3 consecutive months, for 2 consecutive years.

Risk Factors for COPD

• Tobacco smoke accounts for 95% of cases in the UK.
• Indoor air pollution.
• Occupational exposures like coal dust, silica, and cadmium.
• Low birth weight and infections.
• Low socioeconomic status.
• Cannabis smoking.

Clinical Features of COPD

• Cough and associated sputum production are usually the first symptoms, often referred to as a 'smoker’s cough'.
• Haemoptysis can complicate exacerbations, but should not automatically be attributed to COPD without investigation.
• 'Pink puffers' are typically thin, breathless, and maintain a normal PaCO2 until the late stage.
• ‘Blue bloaters’ develop hypercapnia earlier and may develop oedema and secondary polycythaemia.

Investigating COPD

• Diagnosis requires objective demonstration of airflow obstruction via spirometry.
• The diagnosis is established when the post-bronchodilator FEV1/FVC is <70%.