title: Volume assured versus pressure preset non-invasive ventilation for compensated ventilatory failure in COPD.
abstract: BACKGROUND
  The addition of domiciliary non-invasive ventilation (NIV) to standard therapy in chronic obstructive pulmonary disease (COPD) patients with compensated ventilatory failure (CVF) is reported to have beneficial effects. Compliance with NIV is an important factor. Volume assured NIV (va-NIV) may improve compliance and ventilation during sleep by automatically titrating ventilatory pressures.
  
  
  METHODS
  A prospective single centre, randomised, parallel group trial comparing va-NIV and pressure preset NIV (pp-NIV) in COPD patients with CVF naïve to domiciliary NIV was performed (ISCRTN91892415). The primary outcomes were arterial blood gases, mean overnight oximetry (mSpO2) and compliance after three months. Secondary outcomes included pulmonary function, exercise capacity and health-related quality of life assessment.
  
  
  RESULTS
  Forty patients were randomised in a 1:1 ratio. The va-NIV median target minute ventilation was 8.4 L/min and pp-NIV median inspiratory pressure was 28 cmH2O. There were no significant differences between groups in primary or secondary outcomes after three months. Mean (SD) PaO2 8.7 (1.7) versus 7.9 (1.7) kPa (p = 0.19), PaCO2 6.7 (0.5) versus 7.3 (1.1) kPa (p = 0.1), mSpO2 89.7 (4.2) versus 89.8 (3.9) % (p = 0.95), compliance 5.0 (3.1) versus 4.7 (3.2) hours (p = 0.8) in va-NIV versus pp-NIV respectively. Patients allocated va-NIV spent fewer days in hospital initiating therapy 3.3 (1.6) versus 5.2 (2.8) (p = 0.02). Both groups showed significant improvements in PaCO2 and mSpO2 after three months treatment.
  
  
  CONCLUSIONS
  Domiciliary va-NIV and pp-NIV have similar effects on physiological outcomes in COPD patients with CVF and both are well tolerated.
authors.affiliation: Respiratory Support & Sleep Centre, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridgeshire CB23 3RE, United Kingdom. Electronic address: nicholas.oscroft@papworth.nhs.uk.
authors.forename: Nicholas S
authors.initials: NS
authors.lastname: Oscroft
authors.affiliation: Respiratory Support & Sleep Centre, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridgeshire CB23 3RE, United Kingdom.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Chadwick
authors.affiliation: Respiratory Support & Sleep Centre, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridgeshire CB23 3RE, United Kingdom.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Davies
authors.affiliation: Respiratory Support & Sleep Centre, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridgeshire CB23 3RE, United Kingdom.
authors.forename: Timothy G
authors.initials: TG
authors.lastname: Quinnell
authors.affiliation: Respiratory Support & Sleep Centre, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridgeshire CB23 3RE, United Kingdom.
authors.forename: Ian E
authors.initials: IE
authors.lastname: Smith
mesh_terms: D000368:Aged; D001784:Blood Gas Analysis; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D063087:Noninvasive Ventilation / Q000379:methods*; D010092:Oximetry; D011175:Positive-Pressure Respiration / Q000379:methods; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D011788:Quality of Life; D012131:Respiratory Insufficiency / Q000209:etiology / Q000628:therapy*; D016896:Treatment Outcome
keywords: Chronic obstructive pulmonary disease; Chronic ventilatory failure; Non-invasive ventilation