| 摘要 |
To ensure that the inner cannula (16) is mated to the outer cannula (4) of a tracheostomy tube (2), a pressure adjusting device is provided to the collar (26) of the inner cannula (16) so as to apply a biasing force against the tabs that extend from the hub of the outer cannula (4). The torque force that is required to assembly/disassemble the inner cannula (16) to/from the outer cannula (4) may be adjusted by increasing or decreasing the thickness of the pressure adjusting device which may be in the form of a spring ring (30) which elasticity is adjustable by varying the thickness thereof. Ramps are provided within the collar (26) of the inner cannula to guide the movement of the tabs relative to that of the collar (26). In addition, stops are provided within the collar (26) for arresting any further movement of the tabs with respect to the collar (26). Indents are further provided within the collar (26) whereat the tabs can rest. By thus applying a biasing force against the tabs while they rest on the indents, absent a deliberate disassemble torque to the collar, the inner cannula (16) will stay securely fixed to the outer cannula (4).</SDOAB >
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