Method of producing catheter assemblies for prevention of blood leakage

摘要

A catheter is provided which deters the backflow of blood between the insertion needle and the catheter cannula by forming the distal end of the catheter hub so as to restrict the inner diameter of the catheter cannula to a wiping fit with the engaged insertion needle. In a first embodiment the distal end of the catheter hub is pre-formed to its desired final inner dimension. The distal end of the hub is stretched to an oversize condition, the catheter cannula is attached to the hub, and the distal end of the catheter hub is heated, causing a stress relief of the previously stretched hub. The distal end of the catheter hub returns to its pre-formed dimension which will mechanically restrict the diameter of the catheter cannula at that point to form the wiping fit with the engaged needle. In a second embodiment the inner diameter of the distal end of the catheter hub is reduced by inserting the distal end of the hub between the opposing faces of a swaging press, which close to compress the hub in one direction. The degree of closure is controlled by the dimension of at least one of a pair of orthogonally opposing swaging press surfaces, which then close to compress the hub in the orthogonal direction. The distal end of the hub is thus swaged to the desired dimension, and the process advantageously produces a finished product without the production of flash material at the intersection points of the swaging surfaces.