Cannula needle for catheter

A breakaway cannula needle for insertion of a catheter therethrough, comprising:

• (a.) a barrel portion defining inner and outer walls, and a central longitudinal axis, the barrel being formed by cold rolling from a flat blank of stainless steel sheet metal stock having outer parallel edges;
• (b.) a longitudinal slit about 0-1 mil wide defined along the barrel portion parallel to the longitudinal axis, and formed between the edges of the rolled blank, the slit defining opposed edges in parallel registry;
• (c.) a continuous groove formed on the inside wall of the barrel about 180.degree. radially of the slit and parallel thereto, at a controlled and uniform depth of about 50%.+-.10% of the flatstock thickness by rolling means;
• (d.) a needle portion provided at one end of the barrel, and defining a forward and rearward end, the slit extending along the barrel to one needle end, and the groove extending along the barrel to the other needle end;
• and,
• (e.) flexing wings attached to the cannula on each side of the slit;
• the flat sheet metal stock being initially grooved in a continuous manner followed by the sequential steps of:
• i. cold rolling the barrel;
• ii. segmenting to form the needle portion;
• and, iii. attaching the wings;
• whereby, the cold rolling work hardens the barrel and embrittles the groove, thereby enabling splitting of the needle along the groove in a uniform manner, and with needle-to-needle uniformity, when the wings are flexed, to enable separation of the needle from the cannula.