Domiciliary Nasal High Flow and Patient Outcomes in Chronic Hypercapnic Respiratory Failure in the United Kingdom

Does Domiciliary Nasal High Flow (NHF) Therapy Improve Patient Outcomes in Chronic Hypercapnic Respiratory Failure (CHRF) in the United Kingdom (UK): A Pre and Post Interventional Study

Chronic hypercapnic respiratory failure (CHRF) in the context of Chronic Obstructive Pulmonary Disease (COPD) and Obesity Hypoventilation Syndrome (OHS) is associated with increased mortality. The availability and effectiveness of domiciliary Non-invasive ventilation (NIV) treatment (when indicated) is key as this treatment can improve quality of life and reduce health-care costs from associated burden of disease. The emerging obesity epidemic means that there is now increased home mechanical ventilation set-ups in patients with obesity related respiratory failure (ORRF), yet there are no alternative treatments for patients struggling with domiciliary NIV.

Domiciliary NHF has been shown to improve health related quality of life in stable CHRF in patients with COPD and improve cost effectiveness yet there are no current studies looking at the use of domiciliary NHF and its outcomes in ORRF.

The study aims to deliver a pre and post intervention study evaluating patient reported and clinical outcomes in patients using NHF over twelve weeks, who have either COPD or OHS and have been unable to use domiciliary NIV. The study wishes to address key outcomes such as quality of life, clinical effectiveness, compliance and acceptability with the use of domiciliary NHF in both of these patient populations.

This study is an investigator-initiated, unblinded, multi-centre, one arm pre and post interventional study evaluating the use of nasal high flow over twelve weeks, upon self-reported quality of life in adults aged 18 and above, with COPD or OHS and CHRF. This is not a comparator trial and will provide preliminary information on the intervention in a group of individuals who cannot comply with current guideline recommended therapy (with all strategies used to address any barriers to current treatment usage).

This study will therefore aim to evaluate if this treatment offers effective outcomes in this difficult to treat population thus reflecting the variations in practice and choices that occur for this group of individuals in real practice.

Ethical approval will be obtained from the research ethical committee of Brighton and Sussex. Informed consent will be obtained from all willing participants.

Inclusion Criteria:

1. All patients with chronic obstructive pulmonary disease (COPD) who meet these criteria for domiciliary NIV:

   - Diagnosis of COPD based on spirometry; The ration of the forced expiratory volume in the first one second (FEV1) to the forced vital capacity (FVC) of the lungs (FEV1/FVC ratio), of ⩽ 0.70

   And either of:

   • i) Recent inpatient admission with acute hypercapnic respiratory failure with persistent hypercapnia (pH ≥ 7.35 and PaCO2 ≥ 6 kilopascal (kPa)) 2-4 weeks after the acute episode or
   • ii) COPD with evidence nocturnal hypoventilation (sleep study demonstrating time under 90% saturations for 30% of the sleep time) or
   • iii) Stable CHRF (paO2 ⩽ 8 kPa and paCO2 ≥ 6 kPa)

   OR

2. All patients with OHS who meet these criteria for domiciliary NIV i) Diagnosis of OHS based on Body Mass Index > 30 kg/m2, daytime hypercapnia (PaCO2 ≥ 6kPa) and significant nocturnal hypoventilation (saturations ⩽ 90% for 30% of the total sleep time) or ii) Inpatient admission with acute hypercapnic respiratory failure requiring NIV referred for consideration of domiciliary treatment

who have been offered treatment with NIV and have:

3)

• discontinued or demonstrated poor compliance with domiciliary NIV (defined as ⩽ 4 hours usage for 70% of the nights at 4 months with all reasonable measures taken to address barriers to treatment use)
• evidence of sleep disordered breathing on a sleep study
• over or equal to 18 years of age
• able to provide informed consent
• able to participate for the duration of the study
• have an expected survival for greater than three months

All patients must meet inclusion criteria for 1 or 2 and all of 3

Exclusion Criteria:

• Unstable psychiatric disease
• Unable to return for review appointments e.g due to move home or lives a long distance from the study site
• Pregnancy
• Receiving home NIV treatment at time of inclusion to study
• Receiving home NIV treatment for other medical illnesses, for example neuromuscular disease
• Unable to read English