"The responses reaffirm the church position that patients in a “vegetative state” are living human beings with inherent dignity and deserve the same basic care as other patients. This basic care would include nutrition and hydration, even when provided through artificial assistance.
“The administration of food and water even by artificial means is, in principle, an ordinary and proportionate means of preserving life,” according to the Congregation’s response. “It is therefore obligatory to the extent to which, and for as long as, it is shown to accomplish its proper finality, which is the hydration and nourishment of the patient. In this way suffering and death by starvation and dehydration are prevented.”
The bishops also asked for clarification as to whether nutrition and hydration could be removed if physicians determined that the patient would never recover consciousness. The Congregation affirmed that the patient must receive “ordinary and proportionate care which includes, in principle, the administration of water and food even by artificial means” regardless of the prognosis of recovery of consciousness."
Possible, but rare exceptions are noted at the link above.