refusing a doctor order

I have a situtation that I am being told I will lose by job if I refuse to follows a dr. order. The order was to place a PICC line on a patient just because she might need it for Amiodrome. She was post op open heart. had not been on any drips requiring central placement for over 12 hours. she still had a cordes in that was going to be removed. The patient was currently on saline drip only. She also had veins for a PIV. I understand about he chain of command and that I must talk to the Dr. and explain why I feel its inapproiate. Needles to say the line was placed and now we are having hugh discussions about NOT being able to say no to this dr. I can not afford to loose my job at this time. I need the medical insurance for my family. Any suggestions???? on how to preceed would be most welcome.