What is Life support? Hope this help you understand.
Life support
From Wikipedia, the free encyclopedia
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 or in some cases during surgery, though life support is employed to stabilize a patient and is typically not sufficient to allow full recovery from their condition.
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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.
http://en.wikipedia.org/wiki/Life_support