| 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 configured for insertion into the first passageway via the first port when the wearer desires to be able to exhale through his or her 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 and from the fifth port during exhalation by the wearer. A valve controls flow through the third port. The valve assumes a first orientation to permit flow from the first port to the second port when the first port is at a higher pressure than the second port, and a second orientation to permit flow from the second port through the third port when the second port is at a higher pressure than the first port. <IMAGE> |
