Respiratory

Acute bronchitis is a usually viral, self-limiting acute cough syndrome caused by temporary inflammation of the conducting airways; the high-yield task is to exclude pneumonia, serious illness and an exacerbation of underlying airways disease before avoiding unnecessary antibiotics.

ARDS is acute diffuse inflammatory injury of the alveolar-capillary barrier causing bilateral pulmonary opacities and severe hypoxaemic respiratory failure not fully explained by cardiac failure or fluid overload; treat the trigger while delivering lung-protective critical care and escalating early when oxygenation remains refractory.

Chronic airway inflammation leaves bronchial smooth muscle hyper-responsive, so airway calibre and expiratory airflow vary over time, with triggers, and with treatment.

Bronchiectasis is permanent bronchial dilatation with impaired mucus clearance, recurrent infection and inflammation; high-quality care combines CT confirmation, aetiology work-up, physiotherapist-led airway clearance, culture-directed antibiotics and specialist prevention of exacerbations.

Persistent airflow obstruction caused by small-airway inflammation and emphysematous loss of elastic recoil, so the lungs cannot empty fully and gas is trapped with every breath.

An acute infection of the lung parenchyma acquired outside hospital that fills alveoli with inflammatory exudate and impairs gas exchange. Confirm the syndrome, assess severity and sepsis risk, and start appropriate antibiotics promptly.

Cystic fibrosis is an autosomal-recessive CFTR disorder in which abnormal epithelial salt and water transport produces dehydrated secretions, chronic suppurative lung disease, pancreatic insufficiency and multisystem complications; modern UK care combines specialist prevention, infection control, nutrition and genotype-directed CFTR modulation.

Empyema is infected pleural fluid, usually arising from pneumonia and progressing from a simple parapneumonic effusion to loculated pus; antibiotics are essential but source control requires image-guided drainage, with intrapleural therapy or surgery when drainage is incomplete.

Interstitial lung disease (ILD) is a heterogeneous group of disorders causing inflammation and/or fibrosis of the lung parenchyma; diagnosis depends on exposure and connective-tissue assessment, HRCT, physiology and specialist multidisciplinary review, while treatment is cause-specific and progression-focused.

A lung abscess is a localised collection of pus within necrotic lung parenchyma, commonly following aspiration of oral flora; it presents subacutely with fever and purulent or foul sputum, and requires prolonged specialist antimicrobial treatment while excluding empyema, obstruction, malignancy, tuberculosis and septic emboli.

A malignant lung tumour can obstruct airways, invade local structures or spread distantly; the high-yield pathway is rapid recognition, tissue and molecular diagnosis, stage and fitness assessment, multidisciplinary treatment and early supportive care.

Obstructive sleep apnoea/hypopnoea syndrome (OSAHS) is recurrent upper-airway narrowing or closure during sleep, causing sleep fragmentation and intermittent hypoxaemia; diagnosis uses sleep history and objective sleep testing, while treatment is tailored to symptoms, severity, comorbidity, safety risk and treatment adherence.

Occupational lung disease is respiratory disease caused or worsened by workplace exposure, spanning occupational asthma, hypersensitivity pneumonitis, pneumoconioses and asbestos-related pleural or malignant disease; the diagnosis changes care because exposure control, specialist referral, workplace protection and compensation pathways become part of treatment.

Fluid in the pleural space can reflect systemic pressure changes, infection, malignancy, pulmonary embolism or other disease; the safe pathway is clinical assessment, ultrasound-guided classification and cause-directed treatment with urgent drainage when pleural infection is high risk.

Air in the pleural space abolishes the negative pressure holding the lung expanded, so the lung recoils inwards, and a one-way leak raises that pressure until venous return fails.

A venous clot, usually from a deep leg or pelvic vein, lodges in the pulmonary arterial tree, obstructing perfusion and abruptly loading the right ventricle.

Gas exchange fails in one of two ways: the lung cannot load oxygen into blood (type 1), or the ventilatory pump cannot clear carbon dioxide (type 2).

Sarcoidosis is a multisystem inflammatory disease characterised by non-necrotising granulomas, usually involving the lungs and intrathoracic lymph nodes; management balances spontaneous remission against progressive, organ-threatening or quality-of-life-limiting disease after infection and malignancy have been excluded.