Adjustable catheter assembly

A method of inserting a catheter into a living subject comprising:

• (A) selecting a catheter assembly comprising:
• a cannula having a distal end portion, a proximal end portion, and a longitudinal duct therethrough from the distal end portion to the proximal end portion;
• a needle having a distal and a proximal end and having a sharpened insertion tip at the distal end, the needle being positioned within the distal end portion of the longitudinal duct of the cannula with the insertion tip extending beyond the distal end of the cannula;
• a catheter inserter having inserter distal and proximal ends and having a cannula guide channel extending from the inserter distal end to the inserter proximal end the cannula being positioned in slidable relationship through the channel such that the distal end portion of the cannula extends beyond the distal end of the channel;
• and
• means for selectively restricting the cannula and needle from sliding relative to the channel;
• wherein at least a portion of the cannula is made of a material which when inserted into a body of a living subject and maintained therein:
• (a)
• (i) softens with a softening ratio of at least about 2:1;
• and/or
• (ii) swells with a swelling ratio of at least about 1.3:1;
• (b) has a tensile energy to break of at least about 700 N-cm/cm.sup.3 ;
• and
• (c) has a 2.5% Secant modulus of less than about 7,000 N/cm.sup.2 ;
• (B) positioning the inserter on the cannula such that the desired length of the distal end of the cannula extends beyond the distal end of the channel;
• (C) engaging the means such that the cannula and the needle are restricted from sliding relative to the channel;
• and
• (D) inserting the needle and the cannula partially into the living subject.