Lower Respiratory Tract

CLINICAL CONTEXT

Lower Respiratory Tract: airway and lung disease, assessment, and care

The lower respiratory tract comprises the trachea, bronchi, bronchioles, and lungs, including alveoli where oxygen and carbon dioxide exchange across the alveolar-capillary membrane. Conducting airways distribute air; elastic lung tissue and respiratory muscles support ventilation; pulmonary vessels perfuse gas-exchanging surfaces. Inflammation, obstruction, fluid, infection, or loss of elastic recoil can impair ventilation, oxygenation, or both. This anatomy helps clinicians interpret cough, sputum, wheeze, chest tightness, pleuritic pain, hypoxaemia, or breathlessness while considering age, smoking and occupational exposure, immune status, aspiration risk, medications, baseline function, and disease trajectory.

Common conditions and patient concerns

Acute bronchitis is usually viral and produces cough, sometimes mucus, chest discomfort, mild fever, or transient wheeze; cough may outlast other symptoms. Pneumonia involves infection and inflammation of lung tissue and may cause fever, tachypnoea, focal crackles, pleuritic pain, hypoxaemia, or delirium, especially in older or frail adults. Asthma causes variable airway inflammation and bronchoconstriction, while COPD commonly involves persistent airflow limitation associated with chronic bronchitis or emphysema. Exacerbations can sharply limit activity and sleep. Pulmonary embolism, pneumothorax, heart failure, lung cancer, interstitial lung disease, and medication effects may mimic or coexist with infection. Ask about onset, exertion, sputum, haemoptysis, fever, chest pain, inhaler technique, prior exacerbations, exposure, smoking, travel, immobility, and daily function.

Conventional evaluation and treatment

Start with work of breathing, respiratory rate, oxygen saturation, haemodynamic stability, mental status, hydration, and ability to speak. Auscultation and percussion can guide but do not independently exclude serious disease. Chest radiography is useful when pneumonia, complication, or another diagnosis is suspected; spirometry confirms persistent airflow obstruction in stable patients rather than during an acute episode. Microbiology, blood tests, blood gases, ECG, or CT should be selected according to severity and the question being asked. Management depends on cause: supportive care for uncomplicated viral bronchitis; appropriate antibiotics for bacterial pneumonia; inhaled bronchodilators and anti-inflammatory therapy for asthma or COPD according to a clinician’s plan; oxygen for documented hypoxaemia; and escalation to hospital or ventilatory support for severe respiratory failure. Pulmonary rehabilitation, vaccination, smoking cessation, and exposure reduction can improve health and reduce future risk.

Complementary support and red flags

Breathing retraining, supervised exercise, relaxation, and nutrition support can complement prescribed care, particularly in chronic disease, but cannot reverse severe airflow obstruction or treat pneumonia or embolism. Steam inhalation can cause burns; herbal preparations and supplements may interact with anticoagulants, inhalers, or other medicines. Patients should discuss these approaches with a clinician and avoid delaying necessary treatment. Emergency assessment is required for severe breathlessness, inability to speak in sentences, blue or grey lips, confusion, collapse, sudden chest pain, coughing blood, rapidly falling oxygen levels, or poor response to a rescue plan. This page supports learning and does not replace local protocols or individual assessment.

Further reading: MedlinePlus: acute bronchitis · MedlinePlus: COPD · WHO: pneumonia

Clinical communication and follow-up

Explain the working diagnosis, important alternatives, planned tests, expected course, and specific safety-netting in language the patient can use. Invite questions about treatment goals, capacity, cost, culture, and complementary therapies. Use a professional interpreter when language access could affect consent or understanding, and confirm clear arrangements for timely clinical review in writing. Document the reasoning, reassess response to treatment, and coordinate care across professions when illness affects more than one system. Teaching anatomy is most useful when it supports this partnership: accurate localisation, respectful listening, timely escalation, and a plan that remains responsive to the individual patient.