Volume assured versus pressure preset non-invasive ventilation for compensated ventilatory failure in COPD

Summary 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 naive to domiciliary NIV was performed (ISCRTN91892415). The primary outcomes were arterial blood gases, mean overnight oximetry (mSpO 2 ) 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 cmH 2 O. There were no significant differences between groups in primary or secondary outcomes after three months. Mean (SD) PaO 2 8.7 (1.7) versus 7.9 (1.7) kPa ( p  = 0.19), P aCO 2 6.7 (0.5) versus 7.3 (1.1) kPa ( p  = 0.1), mSpO 2 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 P aCO 2 and mSpO 2 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.