Fluoroscopy Nasogastric Feeding Tube Placement

Anatomy and Physiology

To fully understand the nasogastric tube placement, it is best to understand the human anatomy that the practitioner traverses during the procedure. Insertion begins at the nares, the outermost part of the nose, also referred to as the nostrils. Once the tube enters the nose, it progresses into the anterior nasal vestibule. The nasal septum, comprised of cartilage, separates the two sides. Beyond the vestibule, the tube has reached the concha. On either side of the concha are the nasal sinuses. This area is approximately 5 to 7 cm posterior to the nares, and it ultimately connects to the nasopharynx posteriorly.[1]

The nasopharynx connects to the oropharynx. The oropharynx runs from the uvula to the mid-epiglottis. From the mid epiglottis to the inferior aspect of the cricoid process is the laryngopharynx. The pharynx, comprised of all three regions, runs approximately 12 to 14 cm in length: from the base of the skull to the start of the esophagus.  The esophagus is about 25 cm in length. At the distal end of the esophagus, the practitioner encounters the gastroesophageal sphincter. Once passed through this sphincter, the tube has reached the stomach. Just beyond the gastroesophageal opening is the cardia region of the stomach. The left and highest portion of the stomach is known as the fundus. The fundus is the area of the stomach that is closest to the diaphragm anatomically.[2] 

The pylorus is the furthest portion of the stomach, connecting it to the duodenum, where gastric contents exit.  The gastric outlet opens and closes via the pyloric sphincter. 

Indications

Many indications exist that necessitate the insertion of a nasogastric tube. Most notably, the need for decompression of the stomach. This procedure is seen in the setting of obstruction, from the pylorus and beyond. Common scenarios include adhesions, internal or incarcerated hernias, ileus, obstructive neoplasm, intussusception, and volvulus, to name a few.[3]

Other medical indications include poison removal or victims of overdose. Unfortunately, these complications can also result in intractable nausea, placing the patient at aspiration risk. The placement of a nasogastric tube can prevent this adverse event. 

Additionally, another clear indication for nasogastric tube placement is for nutrition and/or medicine delivery. Diagnosis and careful evaluation on a case-by-case basis play a key role in decision-making. Clinicians must determine whether a patient can willfully and without resultative complications consume solids and liquids. Those patients most likely to fall into this category are those with a decreased level of consciousness or mental capacity. Furthermore, those suffering from some degree of dysphagia that would result in aspiration would be good candidates as well.[2] These patients might include someone who has suffered a stroke, or head trauma, patients with cerebral palsy, those who have dementia, and premature infants. Another indication for inserting a nasogastric tube is in diagnosing hematochezia in the setting of an upper gastrointestinal bleed.[4]

When considering whether to use the fluoroscopic-guided placement of a nasogastric tube, it is best to consider the patient's anatomy.  There is a clear indication for the use of fluoroscopy when dealing with patients who have advanced head and neck cancer.[5] Patients who have suffered burns or those who have recently undergone esophageal reconstruction would also be a consideration. Insertion of nasogastric tubing, status post esophageal anastomosis, is a protective measure and proves to be very beneficial for the patients. Additionally, it is considered first-line therapy when faced with postoperative anastomotic obstruction and leakage.[6]

Contraindications

Probably the most apparent contraindication of fluoroscopic guided nasogastric tube placement is denied consent. Informed consent is a fundamental construct of autonomy. Autonomy is one of the four principles of biomedical ethics.[7] The medical setting empowers patients with the right to decide of their own free will whether or not they will accept treatment regardless of its medical benefit. Procedural refusal is an absolute contraindication. Another absolute contraindication of nasogastric tube placement, regardless of fluoroscopy guidance, is for patients who have suffered severe craniofacial trauma. This may result in the inadvertent intracranial placement of the tube, causing catastrophic results.[8] 

Some relative contraindications include hemodynamic instability, coagulation abnormality, esophageal varices, recent banding of esophageal varices, severe gastroparesis, Roux-en-Y surgery, and partial gastrectomy.[9]

Equipment

There are two main fluoroscopic equipment types used, fixed and mobile. The fluoroscopic c-arm is a mobile unit consisting of an x-ray source at one end and the image detector at the other. It allows for greater flexibility and choice of location for the operator. However, it is most commonly used for orthopedic procedures. The permanent system uses a radiolucent exam table, with an under-table mounted tube and imaging detector mounted over the top of the table. This system is used most notably for tube insertion when the decision is made to use fluoroscopy. A water-soluble contrast media is used to outline the digestive tract as the tubing is propagated. In the case of difficult anatomy, a guidewire may be utilized to traverse in the direction of choice. 

Several different types of nasogastric tubes exist and can be utilized depending on the purpose of the insertion. The Levin is a single-lumen nasogastric tube with a drainage side port near the gastric tip that is radiopaque for a clear view on imaging.[1] It is generally used for gastric suction, irrigation, and administering nutrition and or medication.

A Dobhoff tube may also be used for this purpose. This tube weights the end, which allows for the advancement of the tube across the pyloric sphincter, taking advantage of the antegrade movement of peristalsis instead of needing manual manipulation. The Salem Sump is a double-lumen tube used primarily for continuous suction, and there is a second tube that opens to the atmosphere to allow for suction.

The Miller-Abbott tube, also a double-lumen tube, has a balloon at the end of one tip and holes at the other. Once advanced into the stomach, the balloon is inflated. The balloon is then advanced through the intestine, and contents are suctioned out. This tube is used for intestinal obstructions. Finally, the Cantor tube is used for intestinal decompression. It contains a balloon at the end of the tip, where mercury is injected. The mercury-filled bag then elongates, allowing for advancement along the intestinal tract.

Personnel

The personnel involved in the proper evaluation and ongoing treatment of patients receiving a fluoroscopic-guided nasogastric tube includes a collaborative team of healthcare professionals. Speech and language therapists assist in the initial assessment of the patient. They evaluate the physical and mental capacity of the individual and determine the necessity and safety of the procedure. They will continue to monitor each patient's progress and determine when or if an enteric tube is no longer needed. Insertion of the tube with fluoroscopy is performed by a radiologist, physician assistant, or nurse practitioner. 

Additional members in the healthcare team include hospitalists, subspecialists, pharmacists, nurses, technicians, community health workers, and emotional, social, and spiritual support providers.

Preparation

Preparation begins with consent, either from the patient or a delegated individual making decisions on behalf of the patient. Once it is agreed to carry on with the procedure, the patient’s medical optimization becomes the next course of action. This includes ensuring that the patient is medically stable before the procedure. With scheduled procedures, the patient should be made NPO 12 hours before reducing the risk of vomiting or, worse, aspiration.

Technique or Treatment

The patient is generally placed in the supine position, although they can also be in the upright seated position. Sedation is uncommonly used; however, fentanyl can be administered intravenously if indicated. Examine both nostrils to identify any septal deviation. The use of 2% topical lidocaine gel for significant pain reduction is recommended, which also provides lubrication for the crossing of the nasopharynx. The tube is inserted into the nares after adequate lubrication, with or without the use of a guidewire, depending on the case.  Fluoroscopy is utilized for real-time visualization as the tube traverses through its path to its final destination in the stomach.[10]

Complications

Fluoroscopy involves the use of ionizing radiation having the same risk profile as x-ray procedures.  A dreaded complication of fluoroscopy is radiation burns which are very rare given the low doses needed for fluoroscopy. Two types of radiation risk are involved with the use of fluoroscopy: Deterministic and Stochastic. Deterministic risks are dose-related and occur at a certain threshold dose. In other words, at a certain level of does, a deterministic side effect is possible in a cause-and-effect relationship. Stochastic risks are directly proportional to the dosage.  This includes cancer resulting from radiation exposure.  The ALARA principle (as low as reasonably possible) is always adopted for procedures requiring the use of radiation. This safety initiative acknowledges radiation exposure as an accepted, integral part of the procedure while minimizing the radiation exposure needed to accomplish the goal.[11]

The advantage of fluoroscopy is that the clinician can advance the tube while visualizing it in real time.  However, there is never a guarantee of proper placement, which may result from human error. In addition, many complications can occur.  Perforation can result at any point along the course of insertion, from the nose to the stomach, which can ultimately result in uncontrolled hemorrhage or infection. 

Less likely a possibility when using fluoroscopy, the tube can be placed in the respiratory tree, resulting in aspiration pneumonia or pneumothorax. Though if the tube is not properly secured, this can become a more common possibility if dislodged.  Other complications with the tube landing in the respiratory tract include bronchopleural fistula, respiratory failure, and even death.   

Additional complications resulting after the proper placement are pressure necrosis of the cartilaginous tip of the nose, rhinitis, conjunctivitis, esophageal varices, and the rare complication of vocal cord injury and paralysis. Vocal cord injury or paralysis occurs due to direct pressure or trauma to the tissue or damage to the recurrent laryngeal nerve. Supraglottic edema can result. This phenomenon is known as nasogastric tube syndrome.[12] Other problems include tube blockage, gastrointestinal diarrhea, and refeeding syndrome.[3]

Nasogastric tube feeding should not be used for more than 4 to 6 weeks because of complications or poor adherence to treatment.[13]

Clinical Significance

Insertion of a nasogastric tube is performed for a multitude of reasons. A variety of techniques exist for performing the procedure. The utilization of fluoroscopy-guided techniques proves beneficial, especially when considering difficult anatomy.  It provides real-time visualization of the procedure as it is happening and decreases the propensity for error resulting in complications.

Enhancing Healthcare Team Outcomes

When considering the procedure, each expert of the healthcare team should understand the indications for the stepwise procedure and the potential outcomes of the fluoroscopic-guided insertion of a nasogastric tube. Additionally, a thorough understanding of the ongoing treatment for each patient is pertinent. Interprofessional communication is paramount to any step of patient care and safety, resulting in improved outcomes.