reprinted from the LifelineLetter (January/February 2014) with permission of the Oley Foundation. http://www.oley.org/
This article will discuss the placement of feeding tubes and how a doctor chooses the right tube for each patient. It includes a review of the types of tubes that are available, the indications for post-pyloric tubes that extend beyond the stomach, and, with post-pyloric tubes, the options of using a gastric tube with small bowel extension versus a tube that inserts directly into the small bowel. Management of tube dislodgement will also be discussed.
Types of Tubes
The choice of tube depends in part on whether the tube is needed on a short-term or long-term basis. Short-term tubes include the naso-gastric (NG) and naso-jejunal (NJ) tubes, which go through the nose and end either in the stomach (NG) or small bowel (NJ). Tubes intended for more long-term use include the gastrostomy tube (PEG, G-tube), gastro-jejunostomy tubes (PEG-J or G-J tubes), and jejunostomy tubes (PEJ, J-tube).
Placing a Tube
Tubes can be placed in a variety of ways. They can be placed surgically by a surgeon; under x-ray guidance by an interventional radiologist; or during an endoscopic procedure by a gastroenterologist.
This article will focus on endoscopically placed tubes. An endoscope is a piece of equipment that has a long tube with a light and camera at its tip. The camera projects images onto a video screen. While a patient is under sedation, the doctor passes the endoscope through the mouth, down the throat into the upper intestinal tract. This allows the doctor to see the inside of the esophagus, stomach, and small intestine, and to pass a tube safely into the intestinal tract.
NG- and NJ-Tubes
Short-term tubes include those that pass down the nose and into the stomach (NG-tube) or into the small intestine (NJ-tube). These tubes must be removed after four to six weeks to avoid complications, such as sinusitis or tissue breakdown within the nasal cavity.
An NG-tube can be placed at the bedside. An NJ-tube, however, is typically placed under endoscopic guidance because the tube must pass beyond the stomach outlet and into the small bowel. Several approaches can be used to position the NJ-tube.
One approach entails placing an NG-tube and then inserting an endoscope along with a forceps or snare device. The doctor will use the forceps to grasp the tube and guide it down into the small bowel with the endoscope. Another approach is to put a guide wire into the small bowel through a channel in the endoscope. The wire remains in place as the endoscope is withdrawn, a tube is passed over the wire, and then the wire is removed while the tube stays in place. A final approach is to pass an endoscope into the small bowel and feed a small caliber (3 mm) NJ-tube through the endoscope channel into the small bowel. The doctor then gradually advances the tube into the small bowel as the endoscope is withdrawn, leaving only the tube in place.
You may be wondering how a tube that is placed endoscopically through the mouth can come out through the nose. Once the tube is in place, the doctor transfers the tube from the mouth up the nose with a special device. Sometimes a pediatric scope, which is very small, allows an alternative. This scope is a little thicker than spaghetti, and the doctor can pass it down the nose instead of going through the mouth as in a normal endoscopic exam. In this manner, the tube can be put right into the nasal passage.
Long-term feeding tubes can remain in place as long as they are needed. These tubes can be divided into two categories: pre-pyloric and post-pyloric tubes. The pylorus is the stomach’s outlet into the small intestine. A pre-pyloric tube refers to a tube extending into the stomach, and a post-pyloric tube is one that extends through the stomach into the small intestine. The two types of post-pyloric tubes include the gastro-jejunostomy tube and the jejunostomy tube.
A gastrostomy tube is a tube that passes through the abdominal wall into the stomach. Often, the initial gastrostomy tube is placed endoscopically by a gastroenterologist. A tube placed this way is called a percutaneous endoscopic gastrostomy, or PEG, tube. To place a PEG tube, the doctor advances an endoscope down the patient’s throat into the stomach. Once the endoscope is in the stomach, its light can be seen on the surface of the patient’s abdomen. The doctor will then push on that spot while looking at the image of the inside of the stomach projected by the endoscope. If he or she can see that the stomach wall is compressed with that motion, the doctor knows this is where the tube should be placed.
Once this site is identified, the doctor sterilizes the skin, injects numbing medicine, and makes a small (1 cm) incision. The tube is then pulled through the stomach and out the abdominal wall. The tube is held in place on the inside by a plastic bolster or a water-filled balloon bolster, and on the outside by a plastic disk that sits on the surface of the abdomen. (See figure 1.)
A gastro-jejunostomy tube refers to a gastrostomy tube with an extension that goes into the small bowel. When placed endoscopically, it is called a PEG-J tube or a JET-PEG, which stands for “jejunal extension through a PEG.” A PEG-J is put in by placing a standard PEG tube (as described above), and then inserting a smaller-caliber tube through the PEG. An instrument is then advanced through a channel in the endoscope, and the doctor will use it to grasp the inner tube and carry it into the small bowel with the endoscope. The doctor then releases the inner tube and carefully withdraws the endoscope, leaving the tube in place. (See figure 2.)
A jejunostomy tube (J-tube) is a tube that is inserted directly into the jejunum, which is a portion of the small intestine. The endoscopic approach to placement is similar to the one used for the PEG tube. The only difference is that the doctor uses a longer endoscope to enter into the small intestine. Once the endoscope is in the small intestine, the doctor will once again look for the light shining onto the surface of the abdominal wall and look for the indentation into the small intestine wall when he or she presses externally on that spot. The doctor will cleanse and numb the skin, make an incision, and pass the tube through.
When to Use a Post-Pyloric Tube
A post-pyloric tube should be considered when there is a contraindication to placing the tube directly into the stomach due to prior surgery; or when there is slow stomach emptying, due either to a mechanical blockage of the stomach outlet or to sluggish stomach motility. Examples of surgeries that make placement of a post-pyloric tube preferable or necessary include prior removal of part or all of the stomach (“gastrectomy”) or esophageal surgery involving removal of part of the esophagus and repositioning of the stomach into the chest to take its place (“esophagectomy with gastric pull-up”). In these situations, a PEG cannot be placed because the stomach is too small, absent, or sitting in the chest cavity rather than the abdomen.
Patients with slow stomach emptying due to impaired motility (“gastroparesis”) should also be considered for a post-pyloric tube since they cannot tolerate infusion of feeds into the stomach without experiencing significant discomfort, reflux, or early satiety. Similarly, if the stomach outlet is narrowed or mechanically blocked, feeding into the intestine beyond the stomach is necessary.
A J-tube can prevent aspiration of tube feeds in patients who have delayed gastric emptying. Importantly, J-tubes do not protect a patient from aspiration of oral secretions. This form of aspiration is common in the elderly and patients with a weak swallow mechanism or impaired mental status.
PEG-J or JET-PEG versus PEJ
The decision to use a gastrostomy tube with small bowel extension tube (PEG-J or JET-PEG) versus a tube that goes directly into the small bowel (a PEJ or surgical jejunostomy) is based on a variety of factors. The first consideration is whether the patient already has an existing PEG tube. Some patients with PEG tubes discover after the fact that they cannot tolerate feeds into the stomach and they need a post-pyloric tube. In such patients, it is possible to convert the PEG to a PEG-J and avoid placing a completely new tube at an alternative site on the abdominal wall (which would also require a new incision).
A second consideration is whether a patient requires a tube in both the stomach and the small intestine. This scenario is common for patients with severe gastroparesis, who need a tube in the stomach to drain gastric juice that can build up and cause vomiting, and a tube in the small intestine for delivery of feeds. In such a patient, specially designed PEG-J systems that have an opening in the stomach portion of the tube and a second opening in the small bowel portion of the tube can be used to meet this dual function. Alternatively, these patients can undergo placement of two separate tubes, a PEG and a PEJ.
Other factors that should be considered when deciding between a PEG-J and PEJ are ease of placement and associated morbidity. PEG-J tubes can be challenging to place and maintain because the small bowel extension can either fall back into the stomach or become clogged due to its small caliber. On account of these problems, repeat procedures to reposition or replace the extension tube are common.
In one study comparing PEG-J and PEJ re-intervention rates over a six-month period, 56 percent of patients with the PEG-J required re-intervention compared with 13.5 percent of patients with a PEJ. Based on these numbers, it seems that a direct PEJ is the better choice. That said, it can sometimes be difficult to find a gastroenterologist who is experienced in PEJ placement. Although the PEJ tube has been around since the mid-1990s and the principles of placement are the same as the PEG, not all gastroenterologists are comfortable performing the procedure. In such instances, a patient might be referred for placement of a surgical jejunostomy instead.
Sometimes a feeding tube can fall out. This can occur when there is a traumatic tug on the tube or if the bolster holding the tube inside the stomach or intestine is a fluid-filled balloon that has degraded. When a tube falls out, the next course of action will depend on how long the tube has been in place.
If the tube has been present for four or more weeks, a mature tract has probably formed between the stomach and the abdominal wall. This means that the stomach (at the site of the tube) has adhered to the internal abdominal wall and will remain adhered even if the tube is removed. This adherence seals the hole in the stomach, preventing gastric contents from leaking into the abdominal cavity. It also keeps the opening in the stomach in a fixed location so a new tube can be easily placed into the tract at the bedside. In this case, tube replacement should be done as soon as possible, since the opening in the stomach or small bowel can close within twenty-four hours of tube dislodgement.
Oftentimes a Foley catheter is used as a replacement tube in the emergency room (ER) when a standard replacement device is not available. The Foley tube can be used for feeding (or drainage) until a standard PEG replacement can be placed. X-ray confirmation of tube position is advised when a dislodged tube is replaced.
I always make sure the patient has a replacement device at home so that if the tube comes out, he or she can bring the new device to my office or the ER for re-insertion. I also offer patients the option of learning how to replace the tube themselves, though many are apprehensive and prefer to come back to the office. I replace tubes with an internal balloon bumper every four months, because the integrity of the balloon decreases over time.
If a PEG tube has been in place for less than four weeks and the stomach has not adhered to the abdominal wall, the stomach will fall away from the wall when the tube is removed, leaving the hole in the stomach uncovered. The unsealed hole places the patient at risk for leakage into the abdominal cavity and associated infection. Further, a new tube cannot be safely passed back through the abdominal incision and into the stomach if the stomach hasn’t adhered to the wall. It could result in the tip of the tube sitting in the abdominal cavity rather than in the stomach. Instead, the patient should be hospitalized, started on antibiotics, and observed for infectious complications; a surgical intervention is sometimes required.
These principles apply to dislodged G-tubes, PEG tubes, PEJ tubes, and PEG-J tubes. The one additional factor that needs to be addressed with the PEG-J is replacement of the small bowel extension, which can be done endoscopically or under X-ray guidance.
If a patient requires a long-term PEG or PEJ, he or she may be a candidate for a low-profile device (“gastrostomy button”) when it is time to replace the first tube. Unlike the standard G- or J-tube, the low-profile device rests flat on the skin surface. The user connects extension tubing to the low-profile device during feeds. The device consists of a short tube (1 to 5 cm) with an inflatable balloon or a “mushroom” bolster on one end (inside the stomach or intestine) and a capped feeding port on the other end.
Although the low-profile device is often more desirable, it is usually not placed as the initial tube in adults. Instead, a standard tube is placed. It is removed two to three months later (after the tract has matured) and replaced with a low-profile device. This approach is preferred because it is difficult to estimate the distance between the patient’s stomach and the outside of the abdominal wall. Having the standard tube in place first allows us to make this measurement and order the proper size low-profile tube. Proper fit is important because if the tube is too tight it can create an ulcer in the stomach and lead to tube dislodgement, and if the tube is too loose it can result in gastric contents leaking onto the skin surface.
Table 1: Types of Tubes
Short -Term Tubes
gastrostomy tube (G-tube)
gastro-jejunostomy tube (GJ-tube)
- Feeding tubes can be placed surgically, endoscopically, or radiographically. In most hospitals, the endoscopic approach is first line, since it is minimally invasive and readily available.
- When a tube is placed endoscopically through the skin, it is termed a percutaneous endoscopic-gastrostomy (PEG), -jejunostomy (PEJ), or -gastro-jejunostomy (PEG-J or JET-PEG).
- Pre-pyloric tubes terminate in the stomach while post-pyloric tubes terminate in the small intestine. Post-pyloric tubes are indicated when there has been prior stomach surgery that precludes placement of a gastrostomy tube, and when a patient cannot tolerate tube feeding into the stomach due to impaired stomach emptying.
- The choice of a PEJ versus a PEG-J depends on a variety of factors, including the presence of a pre-existing PEG, the need for a single tube to both drain the stomach and feed the intestine, and the expertise available for tube placement.
- When a single tube for feeding into the small bowel is needed, a PEJ is often preferred since the small bowel extension tube of the PEG-J tends to fall back into the stomach or become clogged.
- Low-profile devices should be considered as a replacement tube in patients requiring long-term enteral access.
- If a tube becomes dislodged, a patient should seek immediate medical attention. A long standing tube can be easily replaced at the bedside, but this must be done as soon as possible to keep the tract from closing. A new tube (less than four weeks old) cannot be replaced at the bedside and dislodgement could lead to more serious complications.
LifelineLetter, January/February 2014