Does the Catholic Church consider not administering a feeding tube passive euthanasia?

If a person was near death due to a severe head injury, but now only completely incapacitated (as in, unable to respond to stimuli; eyes open, but not tracking; not able to speak or swallow), is it OK to withhold giving that person a feeding tube? Does it matter what the odds for improved health are? And, if it is not OK, how does anyone benefit from the person's continued survival?