A blood access device including a fluid conduit configured to convey a flow of fluid to a target vessel, a second lever element pivotally and resiliently connected to a first lever element such that it may move from a first position to a second position. A biasing force is exerted on the second lever element for moving it from the first position to the second position, and a blocking member may be activated by the second lever element, such that a flow of fluid is decreased when the second lever element is moved from the first position to the second position. The lever elements are configured to be fixed to the target vessel when the second lever element is in the first position, and the second lever element moves to the second position and activates the blocking member if the fixation is at least partially lost.
