I like the sound of a "chemical code." As you said, for the patients that are so fragile that compressions and intubation would cause further injury, it is a good compromise. Plus, if someone bradys down or blocks, or runs PVC's or tachyarrythmias, meds might help.
There is also the insult of doing multiple invasive procedures to an already suffering, not-likely-to-be-viable person. why put them through more? I have seen (as have we all) families that want everything done for great-grandma, who is 90 years old and has been an invalid for years.
Why put the poor soul through anything else?
If the person is relatively young or a victim of trauma, or something similar, then I would say that yes, let's pull out all of the stops and see what we can do for this person. All of my family knows that I do not want to be on a vent longer than 2 weeks (anything that can be reversed can be done during that time, I think). If things don't look good, unplug the vent, call the code, or whatever, and call LifeLink to come get whatever usable parts they want-I won't be needing them anymore, and I'll be in a far better place.
My opinion only...