A portable mains electricity (AC-powered) device, which may include rechargeable batteries, intended to assist noninvasive ventilation (i.e., without use of an artificial airway) using bi-level positive airway pressure (BPAP) during spontaneous respiration for adult/child (non-infant) patients affected by obstructive sleep apnoea (OSA) and/or to treat patients with conditions requiring respiratory assistance in the home [e.g., chronic obstructive pulmonary disease (COPD)]. It is a small desktop unit with controls, and may include a built-in humidifier. The device is intended for use in the home but may also be used in healthcare facilities.