Clinical nutrition support provides nutrients to individuals whose health conditions prevent them from eating enough or properly absorbing food. The two primary methods for this support are enteral and parenteral nutrition, and the choice between them depends on a patient’s specific medical situation.
Understanding Enteral Nutrition
Enteral nutrition, often called “tube feeding,” delivers a liquid nutritional formula directly into the gastrointestinal (GI) tract. This approach is used when a person’s digestive system is functional, but they cannot eat or swallow safely, perhaps due to a stroke, certain neurological conditions, or a throat blockage.
For short-term use, a nasogastric (NG) tube is inserted through the nostril into the stomach, or a nasointestinal tube is placed into the small intestine. For long-term support, tubes can be surgically placed directly through the abdomen into the stomach (gastrostomy or G-tube) or the small intestine (jejunostomy or J-tube).
These feeding tubes deliver nutritionally complete formulas to meet a person’s full caloric, vitamin, and mineral needs. Using the GI tract helps maintain gut function and the integrity of the mucosal barrier, which supports the body’s immune responses.
Understanding Parenteral Nutrition
Parenteral nutrition is a method of feeding that bypasses the digestive system by delivering a liquid nutrient solution directly into the bloodstream through a vein. This approach is necessary when a person has a non-functional GI tract due to conditions like severe Crohn’s disease, a bowel obstruction, or short bowel syndrome. It is also used when the digestive system needs to rest after major bowel surgery.
There are two main types of parenteral nutrition. Peripheral Parenteral Nutrition (PPN) is administered through a small vein, typically in the arm, and is used for shorter-term support because the nutrient concentration it can deliver is limited. The intravenous (IV) catheter used for PPN can irritate the vein and often needs to be replaced frequently.
For long-term needs, Total Parenteral Nutrition (TPN) is delivered through a central venous catheter into a large chest vein. This method allows for a highly concentrated solution that meets a patient’s complete nutritional needs over an extended period. A port may also be surgically implanted under the skin for easier long-term access.
Key Differences and Considerations
The primary difference is their relationship with the gastrointestinal system. Enteral nutrition uses a functional gut, while parenteral nutrition bypasses it entirely by providing nutrients intravenously. This distinction leads to the guiding principle: “if the gut works, use it.”
The route of administration also differs. Enteral feeding uses tubes placed into the GI tract, while parenteral nutrition requires venous access. Inserting an enteral feeding tube is less invasive than establishing the central venous access needed for TPN.
Each method carries different potential complications. Enteral nutrition risks include a dislodged feeding tube, aspiration of formula into the lungs, and gastrointestinal issues like diarrhea. Parenteral nutrition is associated with a higher risk of bloodstream infections and blood clots. Long-term TPN use can also lead to liver complications by reducing the motility of the gallbladder and digestive tract.
Enteral nutrition is the preferred method when a patient’s GI tract is functional. It is less expensive and associated with fewer severe complications than parenteral nutrition, making it a safer and more effective option for many patients.