Abstract: A stopper is provided for preventing blockage of a cannula of an intravenous catheter in-between uses including a hub having a connector for securing to the catheter, and a stylet having a length and a shape configured to fill a lumen of the cannula, where the hub is configured to place the stylet within the lumen of the cannula, and where the stylet is configured to prevent blood from clotting within the lumen of the cannula when inserted in a patient between uses. In some implementations, the stopper can have a movable stylet. In an example, the stylet can have a variable stiffness configured to aid in moving and prevent blockage of the lumen by kinking of the cannula.

Abstract: A cannula apparatus including an outer tube with an elongated body and a groove, an inner tube disposed inside the outer tube and being manipulable through the groove, and a cap including a hole, the cap mounted at one end of the outer tube through the hole, in which the inner tube is freely slidable relative to the outer tube.