Enteral & Parenteral Nutrition (Diet, TPN)

Hi, guys. My name is Sandi, and today we are going to talk about nutrition support. When a patient is unable to get adequate nutrition, we can provide nutrition support in the form of enteral or parenteral nutrition to meet their needs.
Enteral nutrition is nutrition support via the GI tract. It is also commonly called tube feeding since the food is administered via a tube. It can supplement intake or provide sole nutrition. The basic makeup is very similar to regular food, just in a liquid form.

So why would we use enteral nutrition? What are some examples? Indications include an inability to take in adequate nutrition along with a GI tract that is functioning normally. For example, a person with dysphagia who can’t swallow but other than that everything is working well. However, there are some contraindications. In critically ill patients, it’s important that a patient is stable prior to starting tube feeds. For example, waiting until after a patient is volume resuscitated and hemodynamically stable.

We want to make sure there is adequate blood flow to the gut. Look for vital signs returning to normal, IV fluid administration stabilizing, a mean arterial pressure over 70 milliliters per mercury, and discontinuation of pressers. Another contraindication is aspiration risk. Signs that might aggravate aspiration risk include a history of aspiration, decreased level of consciousness, vomiting, intubation, and high gastric residuals.

Lastly, we have signs of GI distress. The following signs may warrant delay in the initiation of tube feed: a distended abdomen and G-tube drainage that’s over 500 to 1000 milliliters per day or high-pitched bowel sounds.

Now let’s discuss our access route. There are a number of different placement options for feeding tubes. First, we need to consider the insertion site. Second, the placement or end of the tip of the feeding tube. An orogastric tube is placed in the mouth and through to the stomach. So the first part, oro, refers to the entry point, and the second part is where the tip of that feeding tube ends up, gastric, stomach.

Gastrostomy tubes are inserted through the abdominal wall into the stomach. They can be placed either surgically or endoscopically. A common G-tube called a percutaneous endoscopic gastrostomy, or PEG, tube is an example of an endoscopic placement. PEG tubes can also have a jejunal extension called a PEG-J, which can section or decompress the stomach and then feed into the intestines. Placement is determined by GI function, medical history, aspiration risk, duration of feeding.

So for aspiration risk and stomach issues, you can feed past the stomach and into the intestines. So right down there. For duration, naso and oro feeding tubes are used for shorter-term feedings, and G-tubes for longer-term feedings.

I want to add one more thing on tube size. Tube size is dependent on the patient and the purpose. If we want to put meds through it, we need a larger tube. Can’t put meds through a small bore.

Once the tube is placed, a formula type needs to be chosen. It’s very important to work with the rest of your interdisciplinary team. Typically, the doctor or dietician will place an order for a specific formula type as well as the goal rate for the formula.

So let’s discuss the differences of the formulas. Enteral nutrition formula concentration is designated by kcals per milliliter. So I’ll just write that on here. Standard formulas are typically 1.0 or 1.2, which means there is, for example, 1.0 kcals or kilocalories for every milliliter. So 240 milliliters has 240 calories. More concentrated formulas can go up to 1.5 or 2.0.

Higher-fiber formulas can help regulate the bowels. Elemental formulas contain nutrients that are partially broken down, peptides instead of full proteins, and they’re typically used with patients that have GI issues like malabsorption or pancreatitis. Immune-enhancing formulas contain arginine and omega-3 fatty acids and are used for trauma, surgical or critically-ill patients.

Lastly, we have disease-specific formulas. Most common are renal, diabetes, and respiratory. Renal is more concentrated, low protein, potassium, phosphorous. Diabetes is lower in carbohydrates, and respiratory are higher in fat with the intent of minimizing metabolism byproducts that need to be exhaled by the lungs.

Now, we consider how to administer. Bolus feeds mimic how we eat. Feeds are around 200 to 400 milliliters four to six times per day, delivery between 15 and 30 minutes. It’s a great method for patients that are ambulatory because it gives them more freedom. They’re not tied to a pump.

Intermittent feeds are similar to bolus; however, instead of running for 15 to 30 minutes, they may run over an hour.

Cyclic feeds are typically run between 10 to 18 hours, and they can go up to 150 milliliters per hour in their rate. They’re helpful in a home setting for people that want a bit more freedom during the day but maybe can’t tolerate the larger bolus feeds. They’re also helpful for patients that are trying to take in some foods by mouth to help transition because a continuous feed can possibly affect the appetite.

Continuous feeds are set at a specific rate and delivered over a 24-hour period. They are appropriate for patients that can’t handle a larger volume, and they are also used for feeds into the intestines. You can’t do bolus feeds into the intestines.

Now let’s discuss how to initiate and wean tube feedings. First three initial checks. The placement of the tube must be verified by radiology. Elevate the head of bed to 30 degrees. I’m going to write that. Really important to elevate the head of bed. Verify GI health. Make sure there’s bowel sounds. For continuous or cyclic, you want to start tube feeds at a lower rate and then advance to goal. So an example would be starting maybe at 20 milliliters per hour and then advancing by 20 milliliters every eight hours until reaching maybe a goal rate of 60.

Then once you monitor for tolerance, which we’ll discuss in more detail on the next slide. Then lastly, let’s discuss weaning the tube feeds. There’s a couple of considerations. You want to hold tube feeds for an hour before a meal. Slowly increase to six small meals a day, and when the tube feed is meeting about a half a need, you want to change to maybe a cyclic or a night feed, and then DC once the tube feed is meeting about two-thirds of needs for a few days.

Now let’s discuss the monitoring. So I’s & O’s, this is particularly important for renal patients. It’s more important also if the tube feed patient is not taking any food or water by mouth. Also we want to check gastric residuals. They’re typically checked every four to six hours. The concern is that residuals that are too high can lead to reflux and aspiration. We now know that residuals up to 500 milliliters are tolerated. However, follow your facility procedure as there is some variance in actual practice.

Focus should be on looking at the whole picture. It’s not just about volume. It’s about evidence of tolerance. A GRV or gastric residual volume of 300 with obvious signs of nausea, distension, reflux is worse than a higher one of, say, 450 where there’s no evidence of any issues.

Daily weight should be taken to assess effectiveness of nutrition in meeting needs over time. Also, to monitor fluid balance. Lab values, you want to check electrolytes, BUN and creatinine and glucose. Oral care is very important for patients that are NPO, especially if they’re not taking anything by mouth.

Bowel health. So here you want to listen for bowel sounds, check for abdominal distension and then, of course, nausea, vomiting, constipation and diarrhea. The tube site needs to be monitored for possible infection.

Then medication administration. The proper procedure here is first stop the feeds. Next, flush the tube with 15 to 30 milliliters of water before, between and after medications and, when possible, use liquid medications.

Complications. GI intolerance, abdominal distension, cramping, pain, nausea/vomiting, constipation, diarrhea, dumping syndrome are all signs of GI intolerance.

Interventions. You can change the formula type, add additional water to help with constipation, administer feeds at room temperature, decrease rate of infusion.

Tube placement or site. Tubes can be placed too far or not far enough. So they can also be mistakenly placed into the lungs instead of the GI tract. Aspiration is a concern. The tube site can get irritated. For example, like the nose or infections around the G-tube site.

Tube clotting or obstruction. Intervention would be water flushes; can’t be stressed enough. Before, between, after meds, every four hours for continuous feeds, before and after bolus feeds, after checking residuals. However, if a clog does occur, use 50 milliliters with a piston syringe. Some hospitals have a commercial declogging agent that can be used. Using soda is not recommended.

Bacterial contamination can lead to food poisoning. Interventions. Wash hands, proper labeling of formula, proper refrigeration, replace formula every 24 hours.

Lastly, metabolic complications like elevated blood sugars, hydration status, or electrolyte imbalance.

Now we will discuss parenteral nutrition, which is nutrition inserted directly into the vein. Since the nutrients in parenteral nutrition don’t go through the GI screening process of digestion and absorption, the consistency of parenteral nutrition is very different. Instead of complex carbohydrates and proteins, it has dextrose and amino acids.

Now let’s discuss the indications and contraindications. Parenteral nutrition should be considered a last resort. If there is another way to get nutrition, go that route. The most common reasons for needing parenteral nutrition are tied to issues with the GI tract not functioning. So here are some examples here. Obstruction, fistula, short bowel syndrome, et cetera.

Contraindications then, of course, include a functional GI tract. If the GI is working, use it. The inability to get venous access. Hemodynamically unstable. The focus here is if glucose or fluids, you want those to stabilize first. Then lastly, if it’s going to be used for seven days or less, it’s not considered worth the risk.

There are two types of access, peripheral and central. When providing nutrition for peripheral access, the formula must be isotonic, which limits how much nutrition you can give a patient. Peripheral is a short-term option. Central is a longer-term option, and hypertonic solution can be used for feeding.

I want to add a note in here to be careful when drawing blood on a TPN patient. Proper procedure if drawing from the same line is to stop the TPN, flush the line with 10 to 20 milliliters of normal saline. Then waste 5 to 10 milliliters of blood before drawing one for sample. It may even be required to change the end of cap before drawing blood. Even if using a different lumen, for example, a double lumen PICC, the TPN should still be stopped. Best practice is to stop the TPN but still use a different line or vein for obtaining a sample, preferably from a different arm. If you don’t follow this procedure, you will end up with a falsely-elevated glucose and electrolytes, and it’s not pretty.

Total parenteral nutrition is typically a hypertonic solution. Due to this, it can only be administered into a central vein. It’s more concentrated because of the dextrose or sugar content. Peripheral parenteral nutrition is isotonic and is lower in dextrose. Both TPN and parenteral nutrition can have lipids, amino acids, heparin and insulin added and electrolytes, multivitamins and trace elements.

One concern with peripheral parenteral nutrition. Since it must be isotonic, patients with fluid restrictions may not be able to get adequate nutrition from the lower rate required to not volume overload the patient. Lastly, very important note to verify the bag that it matches the order.

Parenteral nutrition can be either cyclic or continuous. Continuous runs over a 24-hour period. It can be delivered at a lower rate. Cyclic is better for ambulatory patients and can be run overnight. However, for patients receiving insulin in the bag, wean patient on and off TPN by giving TPN at half-strength for an hour before and after.

One note is that if you stop parenteral nutrition for any significant amount of time for any reason, notify the dietician because they may need to recalculate the next day’s calorie needs.

Now let’s discuss the monitoring. First, your I’s & O’s. Monitor hydration in particular. Daily weights, this will monitor for adequacy of intake and fluid status. Monitoring your vital signs and check your lab values, specifically for electrolyte deficiencies, pH imbalances. Check your glycerides to make sure it’s okay to give lipids. Check your liver function tests. If not good, try cyclic TPN. Check glucose because you can adjust the dextrose or add insulin to the bag. Check your prealbumin. Check BUN and creatinine to make sure the kidneys are good, which can impact decisions on the amount of protein, fluid, potassium, and phosphorous.

Now we’ll move down here to sterile techniques. When changing tube dressings, change the bag and tubing every 24 hours. On to flow rate, make sure that your rate is not too high or too low. Very important. If TPN needs to be stopped, especially for diabetics, make sure to have D5 available to administer when the TPN is off so the patient doesn’t become hypoglycemic.

Lastly, precipitation. If calcium and phos precipitate out of the solution, don’t use the bag. One last thing I want to mention here is that patients sedated on a medication called Propofol, they are receiving fat calories from that medication. So patients on nutrition support, those calories will need to be taken into account. So if there’s any big changes in the rate or it’s just newly started or stopped, let the dietician know.

Parenteral nutrition is administered via the vein, so infection and sepsis are a risk. Mechanical complications include obstruction, air embolism, thrombosis and pneumothorax. Metabolic complications include electrolyte imbalance, high or low volume, blood sugars, high triglycerides, and essential fatty acid deficiencies. Lipids are contraindicated for patients with severe hepatic disease, hyperlipidemia, hypertriglyceridemia.

Abnormal LFTs, make sure the patient isn’t being overfed or try switching to cyclic TPN. Refeeding syndrome. If a patient is malnourished, a syndrome called refeeding can occur. When the body has been depleted of essential nutrition, insulin production slows. When carbohydrates are reintroduced, insulin is produced. Insulin moves glucose, phos, magnesium, potassium into the cells, which can lower the serum levels of those.
So that is our nutrition support lesson, and I want to leave you with a few final thoughts. We have a common saying in the hospital. That is, if the gut works, use it. That is always the best option if it is an option. There are a lot of things that can be adjusted if a patient is not tolerating feedings. Pass along any information that you have to the rest of the healthcare team.
Now go out there and be your best self today, and as always, happy nursing.