A patient interface device 20 for a ventilator system comprising: a therapy outlet 22 for delivering pressurised air to a patient； a first port 28 for attachment to a first gas line 42 that’s in fluid communication with the therapy outlet 22； and a second port 26 positioned within the first port 28. Second port 26 is in fluid communication with the therapy outlet 22, where second port 26 is for attachment to a second gas line 46. Each port 28&26 is fluidly connected to therapy outlet 22 for delivering pressurised gas thereto and/or receiving exhaled gas therefrom. Interface 20 may comprise a third port 24 in fluid communication with a pressure outlet 23 that’s adjacent the therapy outlet 22, the third port 24: being positioned within the first port 28； and for connection to a pressure monitor. Interface 20 may comprise an auxiliary exhaust port 32 having a removable closure 33. Interface 20 may comprise a nasal prong device attached to therapy outlet 22 for engaging patient nares to deliver nCPAP therapy. Also, a system for delivering a plurality of respiratory therapy modes, comprising a patient-interface-device 20, a connector-system and a conduit-system. First-port 28 described as an exhaust port.
