| 摘要 |
A safety cannula which is arranged to be fitted to a hypodermic syringe, a catheter or other similar medical appliance. The cannula comprises a hollow hub (31) which is connected with a hypodermic needle (23) and a sleeve (32) which is located about the hub (31). The sleeve is slidable longitudinally between a first position at which it exposes the needle (23) and a second position at which it surrounds the needle (23). The hub (31) and the sleeve (32) are provided with integrally formed latching elements in the form of projections (56 to 58) on the hub (31) and groove-like flutes (60, 61, 64, 67, 68 and 69) within the sleeve (32). The latching elements interengage when the sleeve (32) is in the first position and may be disengaged when the sleeve (32) is in the first position. Also, the latching elements provide for longitudinal movement of the sleeve (32) relative to the hub (31) from the first to the second position, and they provide positive interengagement to prevent further movement of the sleeve (32) relative to the hub (31) when the sleeve (32) has been moved from the first position to the second position.
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