A one-piece respiratory device that is low-cost, light-weight, consumes low or no power, and doesn’t need trained operators. It comprises a shell enclosing the front and side parts of the patient’s chest and abdomen a bellows fixed directly atop the shell to reduce dead space and power requirement one or more openings on the shell to allow exchange of air enclosed between shell and body with the said bellows a sealing mechanism to seal the shell to the patient’s body and an actuating mechanism to actuate the bellows. The actuating mechanism may be motorized and/or manually operated. The device may comprise a spring mechanism to aid the passive recoil of the lungs during exhalation. The device may comprise an electronics assembly to aid synchronous actuation of the bellows with the patient’s inspiratory effort, and to aid ventilation according to pre-set mandatory breaths per minute, in motorized and manual modes.