What is the difference between PN and en feeding?

According to the American Society for Parenteral and Enteral Nutrition (ASPEN), the choice between enteral and parenteral nutrition depends primarily on the functionality of the patient's gastrointestinal (GI) tract. Understanding the difference between PN and en feeding is crucial for medical professionals and patients, as it dictates the method of delivering essential nutrients.

Quick Summary

This article details the core differences between parenteral (PN) and enteral (EN) feeding, from their administration routes and required equipment to their respective indications, risks, and overall complexity. It provides a comprehensive overview of how each method is used to provide nutritional support.

Key Points

• Route of Administration: PN bypasses the digestive system by delivering nutrients intravenously, whereas EN delivers nutrients directly into a functional gastrointestinal tract via a tube.

• GI Tract Function: EN requires a working GI tract capable of digestion and absorption, making it the preferred method when feasible. PN is necessary when the GI tract is non-functional due to conditions like intestinal failure or obstruction.

• Infection Risk: PN carries a higher risk of serious bloodstream infections due to direct venous access, while EN has a lower infection risk but a higher risk of aspiration and other GI-related complications.

• Complexity and Cost: EN is generally simpler to manage and less expensive than PN, which requires stricter sterile techniques and more complex monitoring of metabolic levels.

• Clinical Application: The choice between PN and EN is a clinical decision based on the patient's condition, the integrity of their GI tract, and the anticipated duration of nutritional support.

Parenteral (PN) and enteral (EN) feeding represent two distinct methods of delivering nutrition to patients who are unable to consume food orally. The most significant distinction lies in the delivery route: PN feeding bypasses the digestive system entirely, while EN feeding utilizes it. This fundamental difference has cascading effects on the procedures, equipment, complications, and overall clinical suitability of each method. For example, a patient with a fully functional GI tract but an inability to swallow, such as after a stroke, would typically be a candidate for EN feeding. Conversely, a patient with severe intestinal failure or a bowel obstruction would require PN feeding because their GI tract cannot be used.

Enteral Nutrition (EN) Explained

Enteral nutrition involves delivering liquid nutrients directly into the gastrointestinal (GI) tract, typically through a feeding tube. The GI tract must be functional and accessible for this method to be viable.

Types of Enteral Feeding Tubes

• Nasogastric (NG) tube: Inserted through the nose and into the stomach.
• Nasoenteric tubes: Placed through the nose and extending into the small intestine, such as a nasojejunal (NJ) or nasoduodenal (ND) tube.
• Gastrostomy tube (G-tube): A surgically placed tube that goes directly into the stomach through the abdominal wall. A common type is the Percutaneous Endoscopic Gastrostomy (PEG) tube.
• Jejunostomy tube (J-tube): A surgically placed tube that goes directly into the jejunum, a part of the small intestine.

Advantages of EN Feeding

As the more physiological approach, EN is generally the preferred method when possible.

• Lower risk of infection: Infections are less common with EN compared to PN, as it does not involve continuous access to the bloodstream.
• Supports gut integrity: Regular use of the GI tract helps maintain the normal function and integrity of the gut, which is vital for immune health.
• Cost-effective: EN is less expensive than PN due to simpler equipment and less complex nutritional formulas.

Disadvantages of EN Feeding

• Gastrointestinal complications: Patients may experience issues like nausea, diarrhea, vomiting, or constipation.
• Aspiration risk: A primary concern, especially with gastric tubes, is the risk of tube feeding formula entering the lungs.
• Tube-related problems: Complications can include tube clogging, dislodgement, or skin irritation at the insertion site.

Parenteral Nutrition (PN) Explained

Parenteral nutrition, also known as intravenous feeding, delivers a liquid nutrient solution directly into the patient's bloodstream, completely bypassing the GI tract. This is used when the GI system is non-functional, impaired, or needs complete rest.

Types of Parenteral Nutrition Access

• Total Parenteral Nutrition (TPN): Provides all of a person's nutritional needs intravenously. Due to its high concentration, it requires insertion into a large, central vein via a central venous catheter.
• Peripheral Parenteral Nutrition (PPN): Provides partial nutrition and is delivered through a smaller, peripheral vein, usually in the arm. The concentration is lower than TPN, and it is used for shorter periods.

Advantages of PN Feeding

• Direct nutrient delivery: Ensures nutrient absorption even if the patient's digestive system is severely compromised or not functioning at all.
• Life-saving intervention: Crucial for patients with conditions like severe Crohn's disease, short bowel syndrome, or bowel obstruction.
• Allows gut rest: Provides complete nutritional support while allowing the GI tract to heal from illness or surgery.

Disadvantages of PN Feeding

• Higher risk of complications: Infections, particularly central line-associated bloodstream infections (CLABSIs), are a serious risk.
• More complex management: PN requires careful monitoring of fluid balance, blood glucose, and electrolytes, as well as strict sterile technique.
• Metabolic issues: Risks include liver disease, gallbladder problems, and imbalances in blood sugar and electrolytes.

Comparison Table: PN vs. EN Feeding

Feature	Enteral (EN) Feeding	Parenteral (PN) Feeding
Delivery Route	Directly into the gastrointestinal (GI) tract via a tube.	Directly into the bloodstream via a vein.
GI Tract Function	Requires a functional GI tract.	Bypasses the GI tract when it is non-functional.
Equipment Used	Various feeding tubes (e.g., NG, PEG, J-tube).	Intravenous (IV) catheters (e.g., central line, PICC line).
Risk Profile	Lower risk of infection; higher risk of aspiration and tube issues.	Higher risk of infection, metabolic complications, and venous access problems.
Complexity	Generally simpler and less complicated.	More complex, requiring strict sterile protocols and monitoring.
Cost	Less expensive.	Significantly more expensive due to complex formulas and equipment.
Preferred Use	When the GI tract is functional but oral intake is insufficient or unsafe.	When the GI tract cannot be used due to severe disease or obstruction.
Primary Benefit	Supports gut health and is more physiological.	Ensures nutrition when the gut is compromised.

Clinical Considerations for Choosing Between PN and EN

The decision to use PN or EN feeding is made by a healthcare team, which includes doctors, dietitians, and nurses. Several factors influence this choice:

1. Status of the GI Tract: The most critical factor. Is the patient's gut able to digest and absorb nutrients? If yes, EN is the first choice.
2. Duration of Nutritional Support: For anticipated short-term feeding (e.g., less than 4-6 weeks), less invasive methods like a nasogastric tube might be used. Longer-term needs may point towards a gastrostomy tube for EN or a central line for PN.
3. Patient's Condition: The severity of the patient's illness and their overall health status play a major role. For critically ill patients, early nutritional support, often starting with EN, is recommended for better outcomes.
4. Risk Assessment: The team must weigh the specific risks of each feeding method against the patient's individual risk factors. For example, a patient with unstable blood sugar might face increased challenges with PN.
5. Combination Therapy: In some cases, patients may receive both enteral and parenteral nutrition simultaneously. This can be used during the transition from PN back to EN as the GI tract function recovers.

Conclusion

The core difference between PN and en feeding lies in their route of administration: PN directly into the bloodstream and EN into the functioning GI tract. This foundational distinction determines the complexity, risks, benefits, and overall suitability of each nutritional support method. While EN is generally preferred due to its lower cost, reduced risk of serious infection, and preservation of gut health, PN remains a vital and life-saving option for patients with compromised digestive function. The optimal choice is always a collaborative decision made by a healthcare team based on a thorough assessment of the patient's clinical needs and condition.

Visit MedlinePlus for more information on total parenteral nutrition.

Frequently Asked Questions

What is PN feeding?

PN feeding, or parenteral nutrition, is a medical treatment that provides nutrients directly into a person's bloodstream through a vein, bypassing the digestive system entirely.

What is en feeding?

EN feeding, or enteral nutrition, is a method of delivering liquid nutrition and calories directly into the gastrointestinal tract using a feeding tube.

Which feeding method is better, PN or EN?

Enteral nutrition is generally preferred over parenteral nutrition when the GI tract is functional because it is safer, more physiological, and less expensive. However, PN is vital when the GI tract cannot be used.

When is PN feeding used instead of EN feeding?

PN is used when the patient's gastrointestinal tract is non-functional or severely impaired, for conditions like bowel obstruction, severe intestinal failure, or when the gut needs complete rest to heal.

Are there different types of EN feeding?

Yes, EN feeding can be administered through different tube types, including nasogastric (nose to stomach), nasojejunal (nose to small intestine), gastrostomy (directly into the stomach), and jejunostomy (directly into the jejunum) tubes.

What are the biggest risks of PN feeding?

The biggest risks associated with PN feeding are serious bloodstream infections, metabolic complications like blood sugar imbalances, and issues related to the venous catheter.

Can a patient be on both PN and EN at the same time?

Yes, sometimes patients are on both PN and EN simultaneously. This is often done when transitioning a patient from PN back to EN as their GI tract begins to function again.