A ventilatory support and resuscitation device for providing short-term ventilatory support, as well as constant flow, pressure cycled ventilatory support for breathing and non-breathing patients is disclosed. The device includes a chamber and at least one port in flow communication with the chamber. The apparatus also includes a flexible diaphragm member positioned within the chamber and configured to seal the port from flow communication with the chamber while seated adjacent to the port, and to flex in response to pressure applied thereto so as to allow flow communication between the port and the chamber while the diaphragm is flexing. A flow restrictor in flow communication with the chamber may also be included. The device may be coupled to a patient adapter, whereby a manometer, entrainment unit, and safety pop-off and entrainment valve may be coupled thereto.