Methods, systems and devices are described for providing mechanicalventilation support of a patient using anopen airway patient interface. The system includes gas delivery circuit andpatient interface configurations to optimizeperformance and efficiency of the ventilation system. A ventilation system mayinclude a ventilator for supplying ventilation gas. Apatient interface may include distal end in communication with a patientairway, a proximal end in communication with ambient air,and an airflow channel between the distal end and the proximal end. A gasdelivery circuit may be adapted to attach to the patientinterface without occluding the patient interface to allow ambient air to flowfrom outside the patient interface to the patientairway. The ventilation gas may entrain air from ambient and from the patientairway.
