This study is looking at whether there is a difference in outcomes using two different types of breathing support in those patients who have chronic respiratory failure (patients who under-breathe).

There is little data to demonstrate which mode of ventilation is better in terms of physiological outcomes and outcome data relating to patient symptoms.

We hypothesize that one type of breathing support: pressure support ventilation would be more comfortable for patients as it more closely matches a patient's own respiratory pattern and and so leads to improved adherence and consequent improvement in quality of life.

Patients with respiratory failure will be randomly assigned to receive either pressure support ventilation or pressure control ventilation for the first 6 weeks and then cross-over to receive the mode not previously used for a further 6 weeks. They will have baseline data recorded and then be followed up after each 6 week block.

Inclusion Criteria:

• Patients with chest wall deformity, neuromuscular disease or obesity hypoventilation syndrome with an FEV1/FVC ratio of >70% and VC <50% predicted or patients with COPD with a FEV1/FVC ratio of <70% an FEV1 <50% predicted

• Stable

  • pH >7.35
  • ESS <18
  • Symptomatically stable with clinical resolution of intercurrent infection: normal C reactive protein, white cell count and afebrile

• Daytime symptoms compatible with nocturnal hypoventilation i.e. poor sleep, morning headache, daytime somnolence, shortness of breath

• Arterial carbon dioxide partial pressure (PaCO2) > 6.0kPa during day with evidence of nocturnal hypoventilation (TcCO2 >7.5KPa or a rise in TcCO2 of >1 KPa)

• No prior domiciliary ventilation use

• Patients with COPD must be established on optimal medical treatment prior to enrolment

Exclusion Criteria:

• Psychological, social or geographical situation that would impair compliance with the schedule
• Patients who have underlying malignancy or severe cardiac dysfunction (ejection fraction <40%)
• Complex OSA