Gastrostomy Tube Replacement

Anatomy and Physiology

During endoscopic placement of a G-tube, a gastroscope is inserted, and air insufflation inflates the stomach. About 2.5 cm below the costal margin and medial to the xiphoid process, an area of maximal transillumination is identified while shining an endoscope light through the anterior gastric wall. A good 1:1 contact is confirmed by firmly applying pressure on this point and visualizing the stomach wall sliding off by this pressure at the same time. Once the site is confirmed, this area is marked with a surgical pen for the incision site. After the tube placement with an endoscope, the mechanism of track maturation includes the anterior gastric wall adhering to the abdominal wall forming a gastrocutaneous fistula.

Indications

The indications of percutaneous endoscopic gastrostomy (PEG) tube replacement are:

• Dislodged PEG tube: If the tube is dislodged within 24 hours, a temporary tube (e.g., Foley catheter) should be placed in the track to prevent track closure which starts occurring anytime between 8 to 24 hours and narrows further as time passes.
• Malfunctioning PEG tube
• Obstructed G-tube not responding to traditional unclogging measures(e.g flushing with water or pancreatic enzymes mixed with bicarbonate solution)

Contraindications

Bedside/blind PEG tube replacement is contraindicated in the following situations:

• G-tube displacement or malfunction within 4 weeks of initial tube placement (due to track immaturity)[2]
• Massive ascites
• Any signs of peritonitis
• Coagulation disorders
• If the tube has been displaced for more than 24 hours, and the track has narrowed or closed

Equipment

For bedside replacement of G-tube:

• G tube (size similar to prior G-tube)
• 10 mL saline syringe
• Guidewire
• Dressing kit
• 2 x 2 and 4 x 4 gauze
• Alcohol swabs and povidone-iodine swabs
• Gastroscope (if endoscopic replacement is being considered)

Preparation

First, if the tube is still in place, it should be examined. There are cases of a malfunctioning tube. It is vital that the clinician take a careful history and review prior records when they are available, to know the type of tube that has been placed (with internal mushroom cap versus internal balloon). The dressing is removed, and the percutaneous incision site is examined for any signs of infection, track closure, or tube displacement in subcutaneous tissue. The area should be appropriately cleaned with sterilizing alcohol or povidone-iodine. The area is covered with either the sheath in the PEG replacement kit or surgical drapes to avoid contaminating the surroundings during PEG replacement.

Technique or Treatment

If the PEG tube is not completely dislodged but has been clogged or malfunctioning, the old tube needs to be removed. If the old tube is an endoscopically placed tube with an internal mushroom tip, then gentle traction is applied to the external portion of the tube to remove the internal mushroom. This has to be done with very gentle traction, and excessive force should be avoided at all costs as it can lead to disruption of even a well-formed track. If unusual resistance is felt during the attempted removal of the tube by gentle traction, it is best to remove the tube after endoscopic cutting of the internal bumper/mushroom cap and removal of the rest of the tube through external puling. If the old G-tube has an internal balloon, the balloon is deflated by aspirating fluid through the balloon port which usually consists of 8 to 10 mL of fluid. After this step, once the tube is removed, a similar size PEG tube is prepared to be inserted.

For replacement G-tube, tubes with the balloon tip are usually preferred to minimize the risk of disruption of the old track. A similar diameter PEG tube as the prior tube should be used as a replacement tube. First, the balloon functioning is confirmed outside the body by injecting 8 to 10 mL of saline in the balloon port. Once confirmed, the balloon is then deflated again. The balloon tip G-tube is either inserted into the track blindly or via the use of a guidewire with or without fluoroscopy and is advanced within the track. Once fully inside, the balloon is inflated with 8 to 10 mL of saline or distilled water. The tube is slowly retracted till gentle resistance is encountered due to the internal balloon opposing the gastric wall. At this point, the external portion of the tube is secured with a dressing. Both ports of a traditional G-tube (feeding port and med port) are flushed and then capped. A dressing is then applied based on institutional policy. It is vital to apply a protective dressing to avoid accidental pulling or dislodgement in patients with altered mentation.

The final step in PEG tube replacement is to confirm the placement. There are certain ways gastric placement can be confirmed. The simplest method is the bedside method of flushing air through the tube and auscultating for gastric gurgle. However, this method is quite unreliable. The most accurate way of confirming internal balloon placement is with an endoscope. However, this might not be cost-effective. The most commonly used technique in most practices is to place water-soluble contrast through the replacement tube and obtain a post-contrast-enhanced abdominal x-ray to confirm placement in the stomach.[3]

Complications

The major complication of PEG tube replacement is accidental peritoneal placement of the tube. Peritoneal tube placement should be suspected after tube replacement or after resuming feeding through the tube, the patient starts having abdominal pain, fever, and signs of frank peritonitis on the exam. If this happens, a prompt investigation should be performed using a contrast x-ray with water-soluble contrast or with a computerized tomography (CT) scan of the abdomen. Tube feeds should be stopped immediately. A surgical consult should be obtained, and broad-spectrum antibiotics should be initiated as soon as possible. The patient is then managed conservatively with close hemodynamic monitoring along with surgical assistance if needed.

Other complications are rare, but the tube replacement site can get infected especially if the balloon is underinflated or not opposing the gastric wall. This can lead to leakage of gastric contents into the track. Bleeding due to trauma during tube replacement is rare but can happen.[4][5]

Clinical Significance

G-tube malfunction is commonly encountered in clinical practice both in inpatient and outpatient settings. At some institutes, G-tube replacement is exclusively done by either the gastroenterology service or interventional radiology service depending on who initially placed the tube. However, if the patient is seen in the clinic, emergency department, or a nursing home for malfunctioning G-tube, an appropriate service, either gastroenterology or interventional radiology, should be consulted. If the tube has dislodged or come out, the gastrocutaneous fistula track will start to close as soon as in 8 hours but definitely in 24 hours. The longer the duration the tube has been out of place, the higher the chances that the track has narrowed or closed. If more than 24 hours have elapsed after G-tube has been displaced, a blind forceful attempt to put a Foley or G-tube should not be done, and replacement should be referred to specialized services (gastrointestinal or interventional radiology). If G-tube has been dislodged for less than 24 hours, consider putting a temporary tube such as a Foley catheter (similar size as G-tube) to prevent the closure of the track and contact a specialty service for replacement. Once the tube is replaced, gastric placement confirmation with contrast-enhanced abdominal x-ray is recommended.[6] If the patient develops any signs of peritonitis after tube replacement, accidental intraperitoneal tube placement should be suspected and further evaluated.

Enhancing Healthcare Team Outcomes

G-tube malfunction is commonly encountered by nurses, physician assistants, nurse practitioners, and physicians in clinical practice. The team should have a working knowledge of how to handle G-tube problems and provide appropriate intervention and assistance in resolving the dysfunction.