Final answer:
Total parenteral nutrition (TPN) is used for patients with very high caloric needs requiring long-term therapy, providing all necessary nutrients directly into the bloodstream. Dehydrated patients may receive an ordinary NaCl solution or a mixture of isotonic saline and sodium lactate intravenously, depending on the nature of their fluid and electrolyte losses.
Step-by-step explanation:
When caloric needs are very high and long-term therapy is indicated, the type of parenteral nutrition usually used is total parenteral nutrition (TPN). TPN is a method of supplying all the nutritional needs of the body by bypassing the digestive system and infusing nutrients directly into the bloodstream. TPN is tailored to the patient's needs, providing carbohydrates, proteins, lipids, vitamins, and minerals. It is particularly relevant for patients who cannot meet their nutritional requirements through oral intake or enteral feeding and for those whose gastrointestinal tracts are nonfunctional.
For patients with dehydration, intravenous fluids are administered. Ordinary sodium chloride (NaCl) solution is commonly given parenterally to correct the fluid losses. However, if the lost fluid is high in sodium and bicarbonate (HCO3), a mixture that includes 2/3 isotonic saline and 1/3 sodium lactate should be given intravenously to effectively manage the patient's fluid and electrolyte balance.