US Patent 7749196 Small gauge needle catheterization apparatus

An apparatus for percutaneous catheterization. The apparatus comprises a catheter, and an inner cannula received within the lumen of the catheter. The inner cannula has a distal portion that tapers toward the distal end, and is sized to extend through the distal opening of the catheter to provide a generally smooth diametrical transition between the distal end of the catheter and the distal open end of the inner cannula. A stiffening cannula is sized to be received in the lumen of the inner catheter, and has an inner diameter sized to receive a wire guide therethrough. The stiffening cannula as a distal section of greater flexibility than the flexibility of a proximal section for providing kink resistance to the apparatus.