A sterile portable device intended to be integrated between a medical gas supply and a face mask/mouthpiece (not included) to assist noninvasive ventilation (i.e., without an artificial airway) using continuous positive airway pressure (CPAP) during spontaneous patient respiration in respiratory emergency situations and/or respiratory therapy settings. It is typically a small plastic unit intended to be used with a separate flowmeter and manometer to establish a gas pressure proportional to gas flow rate through turbulent gas flow in an internal chamber using accelerating micro-channels (a virtual valve); tubing may be included. This is a single-use device.