| 摘要 |
An outer cannula has a first port for orienting outside the neck of a wearer, a second port for orienting within the trachea of the wearer, a first passageway coupling the first port to the second port to permit the flow of gases from the first port to the second during inhalation by the wearer and from the second port during exhalation by the wearer, and a third port between the first and second ports. An inner cannula is provided for insertion into the first passageway via the first port when the wearer desires to be able to exhale through the wearer's pharynx. The inner cannula includes a fourth port for orienting adjacent the first port, a fifth port for orienting adjacent the second port and a second passageway coupling the fourth port to the fifth port to permit the flow of gases from the fourth port to the fifth during inhalation by the wearer. A first valve controls flow through the third port. A second valve assumes a first orientation when the flow of respiration products through the third port is relatively less impeded and a second orientation permitting respiration products to flow from the second port to the first port and out the first port when flow through the third port is relatively more impeded. |
