Nasogastric Tube 

Gastric intubation via the nasal passage (ie, nasogastric route) is a common procedure that provides access to the stomach for diagnostic and therapeutic purposes. A nasogastric (NG) tube is used for the procedure. The placement of an NG tube can be uncomfortable for the patient if the patient is not adequately prepared with anesthesia to the nasal passages and specific instructions on how to cooperate with the operator during the procedure.

Diagnostic

• Evaluation of upper gastrointestinal (GI) bleed (ie, presence, volume)
• Aspiration of gastric fluid content
• Identification of the esophagus and stomach on a chest radiograph
• Administration of radiographic contrast to the GI tract

Therapeutic

• Gastric decompression, including maintenance of a decompressed state after endotracheal intubation, often via the oropharynx
• Relief of symptoms and bowel rest in the setting of small-bowel obstruction
• Aspiration of gastric content from recent ingestion of toxic material
• Administration of medication
• Feeding
• Bowel irrigation

Absolute contraindications

• Severe midface trauma
• Recent nasal surgery

Relative contraindications

• Coagulation abnormality
• Esophageal varices or stricture
• Recent banding or cautery of esophageal varices
• Alkaline ingestion

• Various methods of topical anesthesia for nasogastric intubation have been proven effective in pain relief and improve the likelihood of successful nasogastric intubation.^{[1, 2, 3, 4, 5]}
• The use of viscous lidocaine (ie, the sniff and swallow method) was found to significantly reduce the pain and gagging sensation associated with nasogastric tube insertion.^[6] Viscous lidocaine is discussed in more detail in the Technique section below.
• Alternative techniques include the following:

  • Nebulization of lidocaine 1% or 4% through a face mask (≤4 mg/kg; not to exceed 200 mg per dose in adults) is an option. The authors recommend that a preservative-free lidocaine (ie, intravenous lidocaine) be used for nebulization in order to minimize the risk of allergic reaction.
  • An anesthetic spray that contains benzocaine or a tetracaine/benzocaine/butyl aminobenzoate combination (Cetacaine) may be applied to the nasal and oropharyngeal mucosa. Be advised that incidents of methemoglobinemia after a single use of benzocaine topical sprays have been reported to the US Food and Drug Administration (FDA). For more information, see Anesthesia, Topical.

The following equipment is needed (also see image below):

• Nasogastric tube

  • Adult - 16-18F
  • Pediatric - In pediatric patients, the correct tube size varies with the patient's age. To find the correct size, add 16 to the patient's age in years and then divide by 2 (eg, [8 y + 16]/2 = 12F)
• Viscous lidocaine 2%
• Oral analgesic spray (Benzocaine spray or other)
• Syringe, 10 mL
• Glass of water with a straw
• Water-based lubricant
• Toomey syringe, 60 mL
• Tape
• Emesis basin or plastic bag
• Wall suction, set to low intermittent suction
• Suction tubing and containerEquipment for nasogastric intubation.

• Position the patient seated upright.

• Explain the procedure, benefits, risks, complications, and alternatives to the patient or the patient's representative.
• Examine the patient's nostril for septal deviation. To determine which nostril is more patent, ask the patient to occlude each nostril and breathe through the other.
• Instill 10 mL of viscous lidocaine 2% (for oral use) down the more patent nostril with the head tilted backwards (as shown in the images below), and ask the patient to sniff and swallow to anesthetize the nasal and oropharyngeal mucosa. In pediatric patients, do not exceed 4 mg/kg of lidocaine. Wait 5-10 minutes to ensure adequate anesthetic effect. Aspiration of viscous lidocaine into a syringe. Instillation of viscous lidocaine 2%.
• Estimate the length of insertion by measuring the distance from the tip of the nose, around the ear, and down to just below the left costal margin. This point can be marked with a piece of tape on the tube. When using the Salem sump nasogastric tube (Kendall, Mansfield, Mass) in adults, the estimated length usually falls between the second and third preprinted black lines on the tube, as shown below. Estimation of nasogastric tube length from nostril to stomach.
• Position the patient sitting upright with the neck partially flexed. Ask the patient to hold the cup of water in his or her hand and put the straw in his or her mouth. Lubricate the distal tip of the nasogastric tube as shown. Nasogastric tube lubrication with water-based lubricant.
• Gently insert the nasogastric tube along the floor of the nose and advance it parallel to the nasal floor (ie, directly perpendicular to the patient's head, not angled up into the nose) until it reaches the back of the nasopharynx, where resistance will be met (10-20 cm). At this time, ask the patient to sip on the water through the straw and start to swallow. Continue to advance the nasogastric tube until the distance of the previously estimated length is reached. See the images below. Patient flexing his neck and drinking water while a nasogastric tube is inserted.

  Nasogastric tube insertion.
• Stop advancing and completely withdraw the nasogastric tube if, at any time, the patient experiences respiratory distress, is unable to speak, has significant nasal hemorrhage, or if the tube meets significant resistance.
• Verify proper placement of the nasogastric tube by auscultating a rush of air over the stomach using the 60 mL Toomey syringe or by aspirating gastric content. The authors recommend always obtaining a chest radiograph (as shown below) in order to verify correct placement, especially if the nasogastric tube is to be used for medication or food administration. Auscultation over the stomach. Nasogastric tube in lung.
• Apply Benzoin or another skin preparation solution to the nose bridge. Tape the nasogastric tube to the nose to secure it in place as shown. If clinically indicated, attach the nasogastric tube to wall suction after verification of correct placement. Secured nasogastric tube.

• During insertion, if concern exists that the tube is in the incorrect place, ask the patient to speak. If the patient is able to speak, then the nasogastric tube has not passed through the vocal cords and/or lungs.
• The nasogastric tube may coil in the nasopharynx or oropharynx. If this occurs, or if the tube is difficult to pass in general, try curling the distal end and partially freezing it in a cup of ice so it temporarily holds its curled shape better. Insert the lubricated tube tip through the nose with the curled end pointing downward. Once the distal tip passes into the hypopharynx, the curved tip faces anteriorly. Rotate the tube 180 degrees so that the curved end is pointing posteriorly toward the esophagus. Continue to insert in the usual manner by having the patient swallow water.
• Another option (only in patients who are sedated and paralyzed) is to place 2-3 fingers through the patient’s mouth into the oropharynx. The fingers are used to guide the nasogastric tube into the hypopharynx.
• Lifting the thyroid cartilage anterior and upward might open the esophagus and allow passage into the proximal esophagus.
• A method of freezing a nasogastric tube with distilled water was shown to increase the success rate of insertion for intubated patients.^[7]
• Direct laryngoscopy or video laryngoscopy can aid in placing a nasogastric tube in sedated patients by visualization of the tip entering the esophagus.^[8]
• Although pH, enzyme, bilirubin, and carbon dioxide testing have been used to distinguish respiratory from gastrointestinal placement of nasogastric tubes, none of these methods has enabled detection of tube placement in the esophagus or gastroesophageal junction. Therefore, the authors recommend the routine use of x-ray verification.^[9]
• In patients who are anesthetized, Appukutty and Shroff found that 3 techniques can increase the success rate of nasogastric tube placement. In randomized controlled study in 200 patients, the use of a ureteral guidewire as stylet or a slit endotracheal tube as an introducer increased the success rate compared with controls, although the latter technique significantly lengthened the time for insertion. However, head flexion with lateral neck pressure proved to be the easiest technique, with a high success rate and fewest complications.^[10]

• Patient discomfort

  • Generous lubrication, the use of topical anesthetic, and a gentle technique may reduce the patient’s level of discomfort.
  • Throat irritation may be reduced with administration of anesthetic lozenges (eg, benzocaine lozenges [Cepacol]) prior to the procedure.
• Epistaxis may be prevented by generously lubricating the tube tip and using a gentle technique.
• Respiratory tree intubation
• Esophageal perforation