Abstract: An apparatus and method for intermittent mandatory ventilation therapy utilizing a connecting device to interconnect an intermittent source of pressurized air, a less pressurized continuous source of air, and the respiratory system of a patient. The connecting device has a one-way bleed valve by which, in cooperation with other one-way valves, air from the continuous air source is prevented from entering an expiration tube through which the patient exhales. The bleed valve is placed in the supply tube from the continuous air source to "bleed off" to the surrounding atmosphere the supply of continuous air during patient expiration, thereby permitting a second one-way valve, also in the supply tube from the continuous air source, to close.