Fundamentals - Practice & Skills, part 21: Enteral and Parenteral Nutrition
by Meris Shuwarger BSN, RN, CEN, TCRN August 11, 2021 Updated: June 16, 2022 9 min read
This article covers enteral and parenteral nutrition. You can follow along with our Fundamentals of Nursing flashcards, which are intended to help RN and PN nursing students study for nursing school exams, including the ATI, HESI, and NCLEX.
Enteral nutrition is a method of artificial nutrition where a patient obtains nutrients via their GI tract (by mouth or feeding tube). “Enteral” has the same root word as “gastroenteritis” — “entero” means “referring to the GI tract.” In this situation, we are still delivering nutrition to the GI tract, and the GI tract is still processing the nutrients, but the patient is not eating the food in their mouth and swallowing it.
Enteral nutrition is a preferred option when it is important to keep the GI system functioning — including maintaining gastric motility (the process of food traveling through the digestive tract) and peristalsis.
Peristalsis is the contraction of the stomach muscles and other muscles in the GI tract that move food along, which allows for digestion. Less peristalsis means less gastric emptying, and this can contribute to nausea and vomiting, constipation, and heartburn.
Types of enteral feeding tubes
There are two types of enteral feeding tubes depending how long (duration) they must be used.
Nasogastric tubes are indicated for short-term use. As discussed in the previous blog post, NG tubes can be irritating to the nose and the esophagus over time; they can even cause different types of pressure injuries.
For longer-term use (e.g., more than four weeks), a percutaneous endoscopic gastrostomy (PEG), or surgically placed gastrostomy tube, is necessary.
Percutaneous, means through the skin. A percutaneous tube could include a PEG tube, a G-tube, or a GJ-tube.
Difference between a G-tube and a GJ-tube
A G-tube (gastrostomy tube) gives liquid nutrition, medication, and other fluids directly into the stomach. A GJ-tube (gastrojejunostomy tube) gives liquid nutrition, medication and other fluids directly into the small intestine (the jejunum).
Continuous vs. intermittent feeding
When administering enteral nutrition, there are two options: continuous feeding and intermittent feeding.
Continuous feeding is when nutrition is delivered down the line via pump.
Intermittent feeding is delivered via gravity, pump, or bolus feeding with a syringe.
Note that when increasing the feeding rate, do this slowly until the ordered rate is achieved (per facility policy).
Tube feeding best practices
Before feeding, perform an abdominal assessment and confirm the presence of bowel sounds (to make sure everything is functioning).
Elevate the head of the bed 30° – 45° during feeding and for at least an hour after feeding. This is to reduce the risk of aspiration.
Remember, the only way to confirm that a nasogastric tube is in the correct place is with an abdominal X-ray. Next, measure the length of the exposed NG tube and confirm that it matches the previously documented length (to ensure the tube is inserted fully). Then verify the pH of aspirated contents by aspirating fluid and testing the pH. The gastric environment is highly acidic, so if the tube is correctly inserted in the stomach, a pH test on the aspirated fluid will be less than 5.5 (indicating an acidic environment).
Never instill air into the tube to check its placement. Use the combination X-ray and pH test to confirm proper placement.
Measuring the gastric residual volume (GRV)
An additional task is to aspirate (pull out) all gastric contents with a large syringe before starting a feed to measure the gastric residual volume (GRV). This is in order to measure how much is left in the stomach when it’s time for the next feed. Using this GRV measurement will indicate if it is necessary to alter the frequency of the feeds, or it might indicate that there is a GI problem.
Note that the protocols for this step may vary depending on the facility’s policy (or textbook), but generally, if the GRV is more than 500 mL, the contents are not returned to the stomach and it is necessary to call the provider. For GRVs less than 500 mL, those contents may be returned to the stomach.
Other best practices when administering a feeding tube
Flush the tube with 30 mL water before and after feeding, medications, GRV check, or every 4 hours during continuous feeding
Change delivery sets (e.g., bag and tubing) every 24 hours or per facility policy. This is to prevent microbial growth.
Clean the opening and rim of formula cans before using them, and refrigerate any opened cans that still have formula in them. Discard these opened cans after 24 hours (again, to maintain infection control).
To prevent bacterial growth, limit hang time to 4 hours for open systems and 24 – 48 hours for closed systems (or per manufacturer guidelines).
The National Institutes of Health defines an open system as one that includes ready-to-use cans and powdered or sterilized formulas that require reconstitution with water. A closed system, or ready-to-hang (RTH) system, is a completely closed non-air-dependent collapsible bag system requiring minimal handling and minimal manipulations.
Parenteral nutrition (or total parenteral nutrition, “TPN”) is nutritional support administered through a central line. The prefix “para-” means “around,” so in this nutrition delivery system, the nutrition goes around the GI tract, circumventing or avoiding it.
Check out our medical terminology deck to learn more of these roots — where they derive from and what they mean.The Medical Terminology and Abbreviations Flashcards allow students entering in or currently enrolled in a healthcare-related program to build a strong foundation of medical terminology and abbreviations.
Parenteral nutrition is delivered into the vascular space, i.e., directly into the bloodstream. Note that a central line — either a PICC line or a central venous catheter— must be used, not a peripheral IV.
Parenteral nutrition is indicated for malabsorption (a condition that prevents absorption of nutrients through the small intestine), hypermetabolic state (which can lead to extreme weight loss), malnutrition, and prolonged NPO (fasting).
Have a second nurse verify the TPN bag label and prescription to confirm the correct bag/prescription is being used.
Once parenteral nutrition has begun, gradually increase or decrease flow rate as needed.
Monitor I&Os, daily weights, and electrolyte levels.
It is especially important to monitor glucose levels to ensure the patient is getting enough (but not too little or too much).
You can learn about blood glucose labs and more with our Lab Values Study Guide & Flashcard Index, a list of lab values covered in our Lab Values Flashcards for nursing students, an easy reference guide.
Use IV tubing with a filter, and change the tubing and bag every 24 hours to prevent bacteria growth.
If the next TPN bag is unavailable for a timely exchange, it is important to continue to give the patient glucose. In the event of a late-arriving replacement TPN bag, administer 10% – 20% dextrose/water until it arrives. (This may vary depending on the orders or facility policy.)
Do not administer other fluids or meds through a TPN line.
Monitor the central line insertion site for signs or symptoms of infection or infiltration.
Hi, I'm Meris, and in this video, we're going to be talking about enteral and parenteral nutrition. I'll be following along using our fundamentals of nursing flashcards. These are available on our website levelrn.com. And if you already have a set, I'd invite you to follow along with me. I'm going to be starting on card number 111. Let's get started. So to start off, let's talk about enteral nutrition. So enteral has the same root word as "gastroenteritis," for instance, right? The word "entero" means referring to the GI tract. So when we're talking about enteral nutrition, this means nutrition that is delivered to the GI tract. So, yes, I'm not eating it in my mouth and swallowing and everything like that for myself, but my GI tract is still processing the nutrients. This is preferable when we have an option because this is going to allow us to keep that GI system functioning, keep gastric motility working, peristalsis working, all of that sort of stuff. So this is the preferred method of artificial nutrition. Now, let's talk about the different types. In the last video, we talked about NG tubes. NG tubes are really great if we need short-term feedings. But if we have a patient who is going to need enteral feeds for longer than four weeks, we really should consider a percutaneous, meaning through the skin-- percutaneous tube. So this could be a peg tube, a G tube, a GJ tube. Any of these things you might hear, the reason being NG tubes are going to be very irritating to the nose and the esophagus over time and can even cause different types of pressure injuries.
All right. So moving on, we're going to talk about kind of some best practices for enteral nutrition. So you'll see here on cards 112 and 113, we've got a whole bunch of information, a lot of bold red information, a lot of bullet points as well. So I'm not going to take you through every single one, but I am going to point out some highlights. So first thing is we always want to make sure that when we are administering a feed to a patient, we want the head of the bed to be elevated to 30 to 45 degrees. I'm going to ask you a question, and after I ask it, pause the video, think about the answer, and then click play. Why do we want to have the head of the bed elevated between 30 and 45 degrees? Go ahead and pause. All right. I hope you paused. The answer is because it decreases aspiration risk. Imagine that you are drinking a glass of water while laying flat. You are at high risk for aspiration. Same thing if I'm putting nutrients into your stomach and you're laying flat. We need to sit you up. Big, big, important concept there. Other things is that we need to make sure to aspirate the gastric contents before we start a feed. So every facility, policy, and textbook is going to be a little bit different. But the thing here to know is before a feed, I need to use a syringe, a large syringe, to aspirate, to pull out whatever is left in the stomach. This allows me to measure how much is left in the stomach when it's time for the next feed. This may mean that we need to change the frequency of the feeds, or it might speak to a GI problem. So you're going to want to follow your facility policies, of course. But in general, if it is larger than 500 mls, we're not going to return it to the stomach. We're going to call the provider. But anything under 500 milliliters, we are going to return to the stomach. On the next card here, there's one big thing in bold red, which is that we flush the tube with 30 milliliters of water before and after every feeding with medications, gastric residual volume checks, or, if we have a continuous feed going on, we're going to flush that tube with 30 mls every four hours. Got to change the tubing and delivery sets every 24 hours to prevent microbial growth. And we want to make sure that open cans of formula should be refrigerated and discard them after 24 hours, very important to know so that we can maintain infection control.
All right. Lastly, let's talk about parenteral nutrition. So enteral means the GI tract. So why is that word "parenteral"? Because the word "para" means around. So it's going around the GI tract. It's circumventing or avoiding the GI tract. If you really like knowing what these things mean, I would very much encourage you to check out our medical terminology deck so you can be more familiar with what these roots mean. So "parenteral" means around the GI tract, avoiding it. So this is going to be delivered into the vascular space, i.e., the bloodstream directly, so important stuff. Look, we got a lot of bold and red information here because you've got to know it. Important stuff to know here is that we have to use some sort of a central line for this; we can't be using a peripheral IV. So we need either a PICC line or a central venous catheter-- central line. Huge, huge, huge thing to know here is that because we are giving someone artificial nutrition, we need to be checking their glucose levels. Are they getting enough? Are they getting too much? I'm going to ask you a question. I want you to pause. We have to make sure that whatever is hanging, whatever TPN, total parenteral nutrition, is hanging, is discarded after 24 hours. Why? Go ahead and pause. I hope you paused. The answer is to prevent microbial growth. Bacteria love sugar, and TPN has a lot of glucose in it, so bacteria are very likely to grow there. So I would definitely know that for all of your nursing school exams, [inflects?], and clinical practice. If for some reason the next bag of TPN were unavailable, we would still want to discontinue it after 24 hours, but we need to hang something that has glucose. So here on the card, we say you would want to administer 10 to 20 percent dextrose in water until the next bag is available. And of course, that's going to be per-order and per-facility policy. I hope that review was helpful. If that was, please like this video; it would mean so much to me. And if you have any great tips or tricks or ways to remember things, I'd love to hear them in the comments. And so with the other people watching, I hope you've subscribed to the channel because you want to be the first to know when a new video drops. And the next video in this series is going to be talking about urinary specimen collection, incontinence, and urinary tract infections, really important stuff. All right, thanks so much, and happy studying.
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