Needle assembly and methods useful for epidural anesthesia

A needle assembly for installing a catheter, comprising:

• a) a hollow cannula having a proximal end and a sharp distal end;
• b) a hollow stylet extending through said hollow cannula, said hollow stylet having a proximal end and a blunt distal end with a radial opening and an interior deflection surface near said radial opening;
• c) biasing means for biasing said hollow stylet in a first position where said blunt distal end of said stylet extends beyond said sharp distal end of said cannula, said stylet being movable against said biasing means to a second position where said sharp distal end of said hollow cannula extends past said blunt distal end of said stylet;
• and
• d) direction indicator means coupled to one of said proximal end of said cannula and said proximal end of said stylet for indicating the direction of said radial opening, said indicator means being rotationally fixed relative to said radial opening.

A method for installing a catheter through the epidermis into a body cavity, said method comprising:

• a) providing a hollow cannula with a sharp distal end and a blunt tipped hollow stylet extending through the cannula;
• b) biasing the stylet relative to the cannula in a first position where the blunt tip of the stylet extends beyond the sharp distal end of the cannula;
• c) providing means for indicating when the stylet is in the first position;
• d) pressing the blunt tip of the stylet against the epidermis until the stylet moves back through the cannula exposing the sharp distal end of the cannula;
• e) piercing the epidermis with the sharp distal end of the cannula;
• f) advancing the distal end of the cannula toward the body cavity;
• g) noting when the means for indicating indicate that the stylet is in the first position;
• and
• h) threading the catheter through the stylet into the body cavity.