Final answer:
The subclavian vein is the appropriate site for catheter insertion for starting parenteral nutrition due to its size, accessibility, and lower risk of complications.
Step-by-step explanation:
The nurse should prepare the subclavian vein for catheter insertion when starting parenteral nutrition. This site is preferred for central venous catheter placement due to its large size, ease of access, and lower complication rates compared to other sites like the femoral vein. The subclavian vein is the continuation of the axillary vein and is an ideal location for a long-term catheter used for chemotherapy, parenteral nutrition, or medication administration, as it can accommodate larger catheters that are required to administer these substances. The cephalic vein, a superficial vessel in the upper arm that leads to the axillary vein, and the basilic vein, another superficial vessel located in the upper arm but more medial, are not typically first choices for parenteral nutrition catheter sites. The radial artery is not used because parenteral nutrition requires venous, not arterial, access.