Embodiments of the present invention may provide ventilation to a patient's lung or airway using a nasal ventilation mask, as part of either a non-invasive ventilation system (NIV) or a non-invasive open-airway ventilation system (NIOV). A ventilation mask may include a rigid or semi-rigid manifold housing. A compliant tube may be located within the manifold housing for forming a main gas pathway through the manifold housing. One or more nasal connectors may be fluidly coupled to the main gas pathway in the compliant tube. A system for sensing airflow through a patient's nose may include a sensing port with a distal opening that opens to a main gas pathway. A protrusion on at least one side of the distal opening may protrude into the main gas pathway.