A ventilator system (100/200/300/400) includes an integrated blower (130/230/330). In one case, the ventilator system includes: an inspiration port (122/222/322) for connection to an inspiratory limb (112/212/312) of a dual-limb patient circuit (110/210/310), and an expiration port (142/242/342) for connection to an expiratory limb (114/214/314) of the dual-limb patient circuit; a gas delivery device (120/220/320) connected to the inspiration port to supply a pressurized flow of gas to the inspiration port to generate a positive pressure; and a blower having an inlet (132/232/332) that is operatively connected to the expiration port and configured to be controlled to selectively supply a negative pressure level between 4 and 120 cmH2O to the expiration port, and an outlet (134/234/334) to exhaust gas received from the expiration port. In another case, the ventilator system includes a blower to generate positive pressure/flow to augment flow for noninvasive ventilation.