Enteral feeding is a method of delivering nutrition or medication directly into the gastrointestinal (GI) tract. The term “enteral” refers to the body’s digestive system, which includes the stomach and intestines. This technique is necessary when a patient has a functioning gut but cannot safely or adequately consume enough food by mouth to meet their nutritional needs. Also known as tube feeding, it is a common medical intervention used to ensure patients receive essential calories, fluids, and micronutrients. It allows the bypassing of the oral cavity while still utilizing the body’s natural processes for digestion and absorption.
Defining the Enteral Route
The enteral route is defined by its use of the gastrointestinal tract for the delivery and assimilation of nutrients. This method is fundamentally different from the parenteral route, which bypasses the digestive system entirely, delivering nutrients directly into the bloodstream through an intravenous (IV) line. Utilizing the GI tract is preferred because it is a more physiological way to process nutrients.
Maintaining the function of the gut is a primary advantage of enteral feeding, as the presence of food helps preserve the integrity of the intestinal lining. This preservation prevents “disuse atrophy” of the intestinal wall, which can occur when the gut is not used. By maintaining the mucosal barrier, enteral nutrition helps reduce the risk of systemic infections associated with bypassing the GI tract.
Compared to intravenous nutrition, enteral feeding is associated with fewer complications, a lower risk of infection, and decreased cost. It stimulates intestinal blood flow and promotes the health of the gut-associated lymphoid system. The preference for this route underscores the principle that if the gut works, it should be used.
Methods of Enteral Delivery
The physical delivery of nutrition enterally requires the use of specialized tubes, the placement of which depends on the anticipated duration of feeding and the patient’s specific GI function. For short-term feeding, generally less than four to six weeks, tubes are typically placed through the nose. These include the Nasogastric (NG) tube, which terminates in the stomach, and the Nasojejunal (NJ) tube, which extends further into the jejunum, a part of the small intestine.
Feeding into the small intestine, as with an NJ tube, is often necessary when a patient cannot tolerate feeds directly into the stomach due to issues like poor gastric emptying or a high risk of regurgitation. For long-term nutritional support, tubes are placed directly through the abdominal wall into the stomach or small intestine. The Percutaneous Endoscopic Gastrostomy (PEG) tube is a common option that enters the stomach.
A Jejunostomy (PEJ or J-tube) bypasses the stomach entirely, placing the tip directly into the small intestine. Another variation is the Gastro-Jejunostomy (GJ) tube, which has ports that allow access to both the stomach for drainage and the jejunum for feeding. These surgically or endoscopically placed devices are designed for extended use, providing a more comfortable and stable delivery method than nasal tubes.
When Enteral Feeding is Necessary
The need for enteral nutrition arises when a patient’s gastrointestinal tract remains functional, but their ability to consume sufficient nutrients orally is impaired. A primary indication is dysphagia, or difficulty swallowing, which can be caused by conditions such as stroke, Parkinson’s disease, or head and neck cancers. In these cases, tube feeding prevents the complication of aspiration, where food or liquid enters the lungs.
Enteral feeding is also used for patients with high metabolic demands who cannot meet those needs through regular eating. This often includes individuals with severe burns, major trauma, or those undergoing intensive cancer treatments. In these hypermetabolic states, the body requires significantly more calories and protein to heal and recover.
Other situations involve a depressed level of consciousness, mechanical ventilation, or severe anorexia where the patient is unable or unwilling to take in adequate calories. The feeding tube is used to deliver nutrition when oral intake is impossible, unsafe, or insufficient to maintain health and support recovery.
Nutritional Composition of Enteral Formulas
Enteral formulas are specialized liquid diets designed to be nutritionally complete, providing a balance of carbohydrates, fats, proteins, vitamins, and minerals. These formulas are broadly categorized based on the complexity of their nutrient components, which determines how much digestion is required by the patient.
Polymeric, or standard, formulas are the most common and contain whole, intact proteins and complex carbohydrates. Polymeric feeds are suitable for most patients who have normal digestive and absorptive function.
When a patient has impaired digestion or absorption, elemental or semi-elemental formulas are used. These contain nutrients that are already broken down, such as hydrolyzed proteins (peptides or free amino acids) and simple sugars. The pre-digested nature of elemental feeds makes them easier for a compromised gut to absorb.
Modular components, like specific protein powders or fat emulsions, can also be added to standard formulas. These supplements customize the nutrient profile, such as increasing protein content, without significantly changing the volume.