Home bi-level positive pressure ventilators are equipped with built-in softwares which measure and record specific items such as tidal volume, total ventilation, leaks, respiratory rate, cycles triggered by the patient. These items have not to date been described in a large group of patients under home mechanical ventilation.

Observational study of patients under home positive pressure mechanical ventilation, in a stable condition.

Data recorded by ventilator software is downloaded by specialized nurses during elective home visits, as well as spirometry, results of recent pulse oximetry, ventilator settings, diagnosis, and basic anthropometric data.

Items recorded by ventilator software are: tidal volume, total ventilation, apnea and hypopnea index, leaks, percentage of inspiratory cycles triggered by ventilator, spontaneous and back-up respiratory rates.

Results are reported by diagnostic group. Statistical analysis (univariate and multivariate) aims to determine which variables are related to unintentional leaks, and whether ventilator settings differ significantly between diagnostic groups.

Inclusion Criteria: - All patients with home noninvasive ventilation with bi-level positive pressure home ventilators with integrated software

Exclusion Criteria:

• Hospitalisation or acute exacerbation;
• Ventilation with a device not equipped with built-in software,
• Ventilation with servo-assisted ventilator
• Invasive ventilation (tracheostomy)

Patients treated for at least 3 months in the Geneva Canton Area, followed by the Division of Pulmonary Diseases of Geneva University Hospital, under home ventilation with bi-level positive pressure home ventilators with integrated software for data recording, in stable clinical condition