Generally they would insert a feeding tube directly into the patients stomach or a nasogastric tube, up the patients nose then down into their stomach. These are still the preferred methods of feeding patients who are unconscious or in a coma, it is far cheaper and safer. Additionally TPN's (IV feeding) are not intended to be a long term solution, just a stop gap measure usually. As well as nutritionists and pharmacists work together to produce TPN's that meet all the bodies physiological needs it still is far from an ideal solution.