| 摘要 |
A needle assembly with a needle shield is disclosed. The shield includes a lumen slidable on the needle, a holder and a needle blocking object which moves at least partially into the lumen in order to block distal movement of the needle. A spring biases the blocking object towards the needle axis. Proximal movement of the needle relative to the shield is limited by a restraint in the form of a discontinuity on the needle which abuts the shield, a tether or a tube abutting the needle hub. When the needle shield moves from a non-shielding position to a shielding position, the needle blocking object moves at least partially into the lumen. The needle blocking object is radially and axially constrained in the shielding position. The holder also prevents radial, longitudinal and circumferential movement of the blocking object. In one embodiment, the needle blocking object is a ball. A catheter adapter and tube may be threaded over the needle. The needle blocking object may also lock the catheter adapter to the needle shield, allowing it to be released only when the needle is shielded. |
