Enteral Feeding Tubes

Feeding Tube Indications

Indications for tube feeding require a patient to have a gastrointestinal (GI) tract that is functioning but is unable to meet their nutritional needs via oral ingestion nutrients. When possible the GI tract should be used as it can atrophy and natural gut flora may translocate to the circulatory system which will increase infection risk. While the use of a feeding tube is most commonly used as the sole source of nutrition, it is sometimes combined with oral intake.

More specific indications include:

• Less than 50% of necessary nutritional intake received orally for five days
• Coma
• Severe dysphasia
• Low enterocutaneous fistula output

Feeding Tube Contraindications

Contraindications for enteral tube feeding can vary by the type of tube, insertion point, and duration of tube feeding. In an attempt to lump those more general contraindications together we have provided the following Feeding Tube contraindications.

• High enterocutaneous fistula output
• Shock or severe acute pancreatitis
• Severe dementia
• Advanced cancer
• Partial or full paralyzation of the GI tract
• Intestinal hypomotility
• Failure to thrive
• Intestinal obstruction
• Aggressive nutritional support is not warranted

Types of Feeding Tubes

Feeding Tubes are classified by their intended use as well as the site they are inserted.

Nasogastric Feeding Tube

A Nasogastric Feeding Tube is also commonly called an NG-tube. When a Nasogastric Feeding Tube is used, it is inserted through the nose and passed down through the esophagus and finally into the stomach. Nasogastric Feeding Tubes are used for short-term feeding which typically does not last for longer than 2 weeks.

Gastrostomy Feeding Tube

A gastric feeding tube is used for long-term enteral nutrition administration for patients at low risk for aspiration. A Gastric Feeding Tube works by being inserted through a small incision made into the abdomen and is then pushed into the stomach so feeding can be administered. There are three main variations to a Gastrostomy feeding tubes:

1. PEG Feeding Tube - Percutaneous endoscopic gastronomy feeding tubes are used quite commonly. PEG Tubes are primarily used to establish the tract and stoma site as a placement tube. Percutaneous endoscopic gastronomy tubes have commonly been placed endoscopically but percutaneous placement via interventional radiology can also be identified as a PEG Tube.
2. Standard Gastrostomy Tubes - Commonly called a G-tube or a button, these balloon or non-balloon tubes may be placed in a patient surgically as an initial or also as a replacement tube for enteral feeding. Gastrostomy tubes placed surgically are most commonly done during a laparotomy or open surgical procedure. For patients where surgical feeding tube placement is the only option, a Stamm surgical gastrostomy technique is typically used. Once an initial gastrostomy tube has formed a well-defined tract between the abdominal wall and the stomach, typically taking six weeks, the standard gastrostomy tube is then placed. Tract maturation times may vary from patient to patient.
3. Low Profile Gastrostomy Tube - A lightweight deviation to the standard gastrostomy tube is the Low Profile G-Tube. Adults who are active, pediatric patients, and patients who are at risk of pulling out their feeding tubes will commonly receive a Low Profile Gastrostomy Feeding Tube. There are a few Low Profile G Tubes which are suited for initial tube placement but the majority of them have been designed to be inserted into a matured tract.

Feeding Tube Sizing

Feeding tubes are sized in the French scale or French units. These units are most commonly abbreviated as Fr, but can also be communicated as Fg, FR or F. In French-speaking countries they might use CH/Ch after Charriere, the inventor. 1 French unit is equal to .33 millimeters, so in order to figure the diameter around the feeding tube, you can simply divide the French size by 3. D (mm) = Fr/3 or Fr = D (mm) × 3. A French size of 12 would have a diameter of 4 mm.

French size correlates to the exterior diameter of the feeding tube and not the diameter of the internal channel.

Tube Feeding Calculation

There are a large array of different tube feeding formulas which can be used for tube feeding but it's crucial to understand the nutritional needs of the patient. Once you know the amount of formula they should be receiving in a 24 hour period, the rate of feedings can then be calculated.

1. First, you will need the patient's weight in both pounds and kilograms. You can convert pounds to kilograms by dividing the pound weight by 2.2.
2. Figure the patients height in inches.
3. Using the Harris-Benedict Formula, we will now calculate the patients daily caloric requirement. We will first figure need the Basal Metabolic Rate, now rather than figuring this by hand, we would recommend using WolframAlpha to make this easy. Click here, and enter in the patients age, body weight, height and gender, then hit enter or the the little equals sign.
4. We will now use the Harris-Benedict Method to determine the number of calories needed daily to maintain current weight. Select the most appropriate weekly exercise level and multiply the BMR accordingly.

Little to no exercise	Daily calories needed = BMR x 1.2
Light exercise (1–3 days per week)	Daily calories needed = BMR x 1.375
Moderate exercise (3–5 days per week)	Daily calories needed = BMR x 1.55
Heavy exercise (6–7 days per week)	Daily calories needed = BMR x 1.725
Very heavy exercise (twice per day, extra heavy workouts)	Daily calories needed = BMR x 1.9




5. Now, in order to figure the tube feeding rate, we will first need to figure the total volume of daily formula. Read the label on the formula to determine the calorie count per milliliter and the volume of the can, the majority of feeding formulas will provide 1 kcal/mL or 2 kcal/mL and are commonly 250 mL cans. Assuming you 1 kcal/mL and 250 mL cans, you will need six cans formula.
6. Figure the rate of tube feeding by now dividing the total volume (1500 in our example) by the feeding duration. If feeding was to be provided for 20 hours of the day, the patient would require 75 mL an hour.

 

Feeding Tube Complications

Complications that may occur with enteral tube feeding cover a broad range which can typically be fall under mechanical, gastrointestinal, metabolic/biochemical and other miscellaneous complications. Additionally, complications with feeding tube use can vary with the type of tube being used.

Nasoenteric Feeding Tube Complications

Since the introduction of fine bore nasoenteral feeding tubes in the 1970's, complications have become far less common. The majority of complications seen are now physical and related to the finer size and varying pliability and materials used with tubes. Tube blockage is a common issue when using crushed medication or when precipitation of protein builds and causes a blockage from inadequate flushing. Additional problems specific to nasoenteric feeding tube use can include the following:

• Nasopharyngeal discomfort
• Gastro-esophageal reflux
• Intracranial insertion - increased risk from modern tubes with internal guide wires
• Development of tracheo-eosophageal fistulas
• Endobronchial placement

Surgical Gastrostomy Feeding Tube Complications

Complications stemming from surgical gastrostomy feeding tubes are more than a few, even though the procedure has been performed for many years. The likelihood of a complication can increase depending on the patient. If patients are elderly, malnourished, suffering from a head injury, stroke, or malignancy, the chances increase; combine that with the use of general anesthesia when performing the gastrostomy can further increase risk.

• Wound dehiscence
• Infection
• Leakage
• Aspiration
• Bleeding

Endoscopic Gastrostomy Complications

PEG feeding tubes have become increasingly more accepted, easier to insert and have a far lower morbidity and mortality rates. Combine those advantages with the fact that PEGs generally will not require general anesthetic and are significantly less expensive than a surgical gastrostomy. Complications from an Endoscopic Gastrostomy include the following:

• Peristomal infection
• Leakage
• Accidental tube removal
• Tube blockage
• Tube fracture
• Tube displacement
• Peritonitis
• Aspiration pneumonia
• Bleeding
• Gastric mucosa overgrowth

Complications and Interventions

The following recommendations should not be substituted for the advice of a medical care professional. Listed below are complications, the possible causes, and potential intervention actions.