A mains electricity (AC-powered) automatic cycling device intended to provide long-term alveolar ventilation support for the full age-range of patients, from neonatal, paediatric to adult, in a critical care setting. It typically uses positive pressure to deliver gas at normal breathing rates and tidal volumes through an endotracheal (ET) tube or tracheostomy, and consists of a breathing circuit, a control system, monitors, and alarms. The inhalation limb includes sites where inspired gas may be heated/humidified, and the exhalation limb includes an exhaust valve to release gas to the ambient air. It can be operated in several modes (e.g., assist/control, synchronized, patient triggered).