Life support, in the medical field, refers to a set of therapies for preserving a patient's life when essential body systems are not functioning sufficiently to sustain life unaided. Life support therapies utilize some combination of several techniques: feeding tubes, intravenous drips, total parenteral nutrition, mechanical respiration, heart/lung bypass, defibrillation, urinary catheterization and dialysis. The same techniques are also used for intensive care, though life support is employed to stabilize a patient and is typically not sufficient to allow full recovery from their condition.
In some cases, skilled nursing care can substitute for one of the above radical therapies, and is almost always preferable if it can be relied upon. For example, some hospitals routinely train nurses to attach oxygen equipment to a patient's preferred breathing orifice, while others limit it to a nose cannula — the cannula is safer from fire than a tent and requires less care than a mask.
In general, enteric feeding ("tube feeding") is preferable to total parenteral nutrition. Urinary catheterization is preferable to dialysis. Mechanical ventilation or defibrillation are preferable to cardiac bypass, and can sometimes substitute for it.
Some consider the practice of artificially prolonging the life an individual who will not recover to to be unethical. Roman Catholic moral teachings suggest that the employment of artificial means is not necessary to fulfil the duty to respect life; however the term "artificial means" may vary in meaning between different schools of thought within and outside Catholicism. Most Catholic theologians however, divide the issue into "ordinary" and "extraordinary" means, and believe that it is an ethical imperative to continue the ordinary means, but ethically neutral to withhold the extraordinary means. They define ordinary means as things like feeding, and extraoridinary means as things like artificial breathing.
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