Chronic Obstructive Pulmonary Disease (COPD) is a common lung disease, affecting 1.2 million people in the United Kingdom (UK). COPD patients suffer with episodes of worsening breathing symptoms called acute exacerbations (AECOPD). Exacerbations occur more often as the disease progresses and are a leading cause of emergency hospitalisation. Patients recovering from exacerbations are at high risk of deteriorating, with one quarter readmitted to hospital within thirty days. COPD thus imposes immense burdens on the National Health Service and patients.

This research will investigate the effects of using humidified nasal high-flow (HNHF) during recovery from severe COPD exacerbations. HNHF delivers warmed, humidified air under flows of up to 60 litres per minute through a nasal interface. This has been shown to improve clinical outcomes, including exacerbation frequency, hospitalisations, breathlessness and quality of life amongst COPD patients with respiratory failure. It is thought to achieve this by improving secretion clearance and providing positive airways pressure which supports the breathing system.

Patients admitted to St Thomas' Hospital, London with COPD exacerbations will be recruited. Prior to discharge, participants will be randomised to receive either usual care alone or usual care plus a HNHF device, which they will be trained to use for a regular period daily. Usual care includes inhalers, steroids and may include antibiotics.

Participants will be followed up for 30-days after hospital discharge using weekly assessments, daily symptom diaries and wrist-worn watch-like devices that detect physical activity. This will enable evaluation of the clinical effects of HNHF on re-exacerbations, readmissions, breathlessness, physical activity and quality of life. Device usage will also be quantified. Participants who receive devices will be interviewed to explore their experiences. After the 30-day home follow-up period, a sub-group of participants will undergo detailed breathing tests during and after exercise to explore the effects of HNHF on the respiratory system.

Inclusion Criteria:

• Emergency hospital admission with a primary diagnosis of AECOPD
• Aged 40-80 years
• ≥10 pack year smoking history
• Body mass index ≤ 35kg/m2
• Cognitively and linguistically able to follow English instructions, provide informed consent and complete the study protocol
• To be discharged home following the hospitalisation in a home environment deemed safe by the investigator to perform home assessments
• Patient lives in the catchment area served by the Integrated Respiratory Team at Guy's and St Thomas' NHS Foundation Trust

Exclusion Criteria:

• Chest radiograph excludes pneumothorax
• Requirement for acute non-invasive ventilation (NIV) during index hospitalisation or established on home positive airway pressure (PAP)
• Significant chronic respiratory failure (PaCO2 >7.0)
• Clinically significant obstructive sleep apnoea requiring treatment
• Allergies to latex, metals or local anaesthetic
• Broken or inflamed skin at the second intercostal space parasternal chest wall areas
• Psychological or social factors that would impair compliance with the study protocol
• Any major non-COPD chronic co-morbidity that may contribute significantly to risk of readmission, including (but not limited to) severe heart failure (left ventricular ejection fraction <30%), malignancy (active treatment or palliation), end stage renal failure and significant neuromuscular disease
• Planned travel away from home in the 30-day post-discharge period