Nasogastric and Feeding Tube Placement

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Chapter 40

Nasogastric and Feeding Tube Placement

Leonard E. Samuels

Nasogastric (NG) intubation is commonly used to evaluate or treat bowel obstruction, ileus, or gastric hemorrhage, preoperatively or postoperatively, or to administer food or medication into the gastrointestinal (GI) tract. Patients with long-term feeding tube complications and those requiring replacement or other manipulation of tubes are frequently seen and treated in the emergency department (ED).

Properties of NG and Feeding Tubes

Polypropylene is the material most commonly used for Levin and Salem sump NG tubes (Fig. 40-1), but it is too rigid for long-term use as a feeding tube. Polypropylene tubes are less likely to kink than others but are more capable of creating a false passage during placement. Latex (rubber) tubes are moderately firm, require greater lubrication for passage, are relatively thick walled, and induce a greater foreign body reaction than do tubes made of other common materials. Latex, especially in latex balloons, deteriorates more rapidly than other material does.¹ Foley catheters are primarily latex, although silicone Foley catheters are available for patients with latex allergies. Silicone tubes are thin walled, pliable, and nonreactive; however, the walls of silicone tubes are weaker and may rupture if fluid is introduced into a kinked tube.² Polyurethane tubes are nonreactive and relatively durable. Rigidity varies from manufacturer to manufacturer, depending on the thickness of the tube. A stylet may aid in the passage of polyurethane and silicone tubes, but it increases rigidity and the potential for tissue dissection, especially with tubes that have a small distal end-bulb.³ Some feeding tubes have weights, which are usually made of tungsten and are nontoxic if released into the GI tract.

Figure 40-1 Salem sump tube. This tube contains a second lumen that allows venting during continuous suction. 1, Pigtail extension (blue) of the air vent lumen; 2, connector for attachment of the suction lumen to the vacuum line; 3, gastric end with suction eyes; 4, insertion depth markers.

NG Tube Placement

Review Box 40-1 Nasogastric tube placement: indications, contraindications, complications, and equipment.

Indications and Contraindications

The simplest NG tube is the Levin tube, which has a single lumen and multiple distal “eyes.” The advantage of the Levin tube is its relatively large internal diameter (ID) in proportion to its external diameter. The theoretical disadvantage is that a Levin tube should not be left hooked up to suction after the initial contents of the stomach have been drained because the suction will cause the stomach to invaginate into the eyes of the tube and thereby blocking future tube function and potentially cause injury to the stomach lining. Levin tubes are therefore rarely used in the ED. The Salem sump tube is preferred over the Levin tube for chronic use as a drainage device because it has a separate (blue-colored) channel that vents the distal main lumen to the atmosphere (Fig. 40-2). This vent helps prevent excessive vacuum from forming at the tip of the tube. Note that both intermittent suction and wall unit vacuum can exceed the venting capacity of the second lumen, so the vacuum setting should be less than 120 mm Hg.

Figure 40-2 Diagram of the Salem sump tube. A, General design. B, Diagram of the double-lumen principle for suction. (A and B, Courtesy of the Argyle Division of Sherwood Medical, St. Louis.)

The major indication for NG tube placement and suction is to aspirate the stomach contents in patients with gastric outlet or intestinal obstruction, gastric or bowel distention, prolonged ileus, or gastric, esophageal, or bowel perforation. Draining the dilated stomach of excessive contents lessens the chance of vomiting and possibly aspiration and provides marked relief of symptoms in patients with intestinal obstruction. The presence or anticipation of depressed mentation potentially justifies NG tube placement to protect the airway, especially if the stomach is full or vomiting is uncontrolled. Bag-valve-mask ventilation often distends the stomach with air, and a postintubation NG tube can improve ventilation, prevent vomiting, and increase patient comfort.

Trauma patients may need an NG tube as part of the evaluation for GI injury or to decompress the stomach before surgery or peritoneal lavage. A radiopaque NG tube may help delineate transdiaphragmatic hernia of the stomach after trauma. A deviated NG tube is a nonspecific sign of traumatic aortic rupture. An NG tube may be used to instill air into the stomach for documentation of a suspected gastric perforation by enhancing visualization of free air under the diaphragm on an upright chest film. In patients unable to swallow, an NG tube may be passed to administer medications or oral contrast material for a computed tomography (CT) scan.

For the evaluation and treatment of upper GI bleeding, indications for NG tubes differ among clinicians, and practices vary widely. Clinical judgement prevails as the best arbitrator, but the true clinical value of an NG tube in patients with GI bleeding is probably less than traditionally promulgated. Although insertion of an NG tube may prompt earlier endoscopy, the procedure has not been demonstrated to improve clinical outcomes.⁴ NG aspiration can help localize bleeding in only a minority of patients with GI hemorrhage. Patients who vomit a significant amount of proven bloody material have had upper GI bleeding; they do not need an NG tube for diagnosis. Such patients are best evaluated by endoscopy, although when a history of bleeding is suspected, stomach aspiration may have a role in diagnosis to confirm the presence of blood. In patients without hematemesis, NG aspiration uncovers less than half the patients with upper GI hemorrhage and thus cannot be used to unequivocally rule out upper GI bleeding. Even a rapidly bleeding duodenal ulcer may not produce blood in the stomach. Some contend that emptying a markedly dilated stomach of blood and stomach contents may reduce the rate of bleeding, but data are lacking. Patients with presumptive upper GI bleeding, which includes those with melena, those younger than 50 years old, and those with a hematocrit lower than 30, need upper endoscopy.^5,6 Patients passing clots or blood per rectum or those with known previous lower GI bleeding are usually experiencing lower GI bleeding.⁶ Except when frankly bloody fluid is obtained, a nasogastric aspirate is diagnostically unhelpful. Small bits of darkish material, bloody mucus, or positive Gastroccult or guaiac tests probably represent sequelae of the procedure, whereas a clear appearance and negative tests still miss most bleeding distal to the stomach. Patients with a bleeding pattern indicative of a Mallory-Weiss tear may need neither an NG tube nor endoscopy.

NG tubes can provide the earliest indication of high-volume esophageal or gastric bleeding. Although variceal rupture may potentially be caused by insertion of instruments into the esophagus, several studies suggest that passage of an NG tube is generally safe, even in patients with esophageal varices. Use of NG tubes for the evaluation and monitoring of upper GI bleeding should be judicious rather than universal.

Increasingly, the literature suggests that most other causes of vomiting are best controlled with medication. Postoperative ileus ends sooner and patients recover faster without an NG tube after various studied abdominal surgeries.⁵ NG tubes prolong the hospital stay, pain, and hyperamylasemia in those with mild to moderate pancreatitis.^7,8 Many patients are better off without an NG tube from the point of view of safety, comfort, and speed of recovery.

In an awake and alert patient with a preserved gag reflex, passage of a NG tube has not been demonstrated to result in significant pulmonary aspiration, even when vomiting occurs during passage. NG tubes are, however, contraindicated in patients with a special predisposition to injury from placement of the tube. Patients with facial fractures who have sustained an injury to the cribriform plate may suffer intracranial penetration with a blindly placed nasal tube.⁹ Severe coagulopathy is a relative contraindication to passage of an NG tube. In patients with a coagulopathy or significant facial or head trauma, an NG tube passed through the mouth may be a better alternative (Fig. 40-3). Patients who have esophageal strictures or a history of alkali ingestion may suffer esophageal perforation. Gagging will decrease venous return and increase cervical and intracranial venous pressure. Comatose patients may vomit during or after NG tube placement. Indwelling NG tubes predispose patients to pulmonary aspiration because of tube-induced hypersalivation, depressed cough reflex, or mechanical or physiologic impairment of the glottis.⁷ Aspiration is also quite common with nasoenteral feedings in debilitated patients, hence the use of a gastrostomy feeding tubes for this condition. An NG tube should be avoided when possible in patients who have undergone gastric bypass surgery or lap banding procedures.

Figure 40-3 A nasogastric (NG) tube may enter the cranium or facial soft tissues in patients with severe head or facial trauma. Those with a coagulopathy may experience significant bleeding from nasal or pharyngeal trauma during passage of an NG tube. In such cases, a standard NG tube inserted through the mouth (as shown above) may be a better alternative.

Extended irrigation of the stomach with water in a patient with upper GI hemorrhage can lower serum potassium levels,¹⁰ and animal studies suggest that cold water lavage can cause rather than control bleeding.^11,12 No study has shown irrigation to be effective in the control of bleeding,^13,14 and vigorous lavage with cold water may lower the body temperature. Erythromycin has been demonstrated to be effective in clearing the stomach for endoscopy,^15,16 and its success is better substantiated than irrigation.

Equipment

Passage of standard NG or feeding tubes can be messy and may be accompanied by coughing, retching, sneezing, bleeding, and spilled water or stomach fluid. For this reason, both the patient and clinician should be gowned; cleanup may be reduced if the bib area is covered with a towel and a supply of tissues or washcloths is available. For standard NG tube placement, a piston or bulb syringe (with a catheter slip-tip) should be available. NG feeding tubes should have a compatible 50- or 60-mL syringe (some are Luer compatible and others are slip-tip compatible).

Tape torn into 4-inch strips or a commercial NG tube holder (e.g., Suction Tube Attachment Device, Hollister, Libertyville, IL) should be handy for securing the tube after placement. Cotton-tipped applicators and tincture of benzoin may be helpful in securing the tube to the nose if the skin is greasy. Make sure that the feeding tube is designed for duodenal passage if this is desired—such tubes are usually longer than regular feeding tubes.

Procedure

Explain the procedure to the patient. Written informed consent is not standard. If the patient is alert, raise the head of the bed so that the patient is upright. Place a towel over the patient’s chest to protect the gown, and place an emesis basin on the patient’s lap.¹⁷ Position the tube (typically a 16- or 18-Fr sump) so that the insertion distance can be estimated, and mark the distance with tape or by noting the markers printed on the proximal end of the tube. A simple method is to measure the tube from the xiphoid to the earlobe and then to the tip of the nose. Then add 15 cm (6 inches) to this number (Fig. 40-4, step 5).¹⁸ It is a common error to fail to estimate the proper length of tube before passage, which can result in the tip of the tube positioned in the esophagus or coiled excessively in the stomach. Check the nares for obstruction. Assess patency by direct visualization, by gentle digital nasal examination, and by having the patient sniff while first one and then the other nostril is occluded. Pass the tube down the more patent naris.

Figure 40-4 Nasogastric tube placement.

Relief of Discomfort

Ameliorate the pain and gagging associated with tube placement by using vasoconstrictors, topical anesthetics, and antiemetics. Because patients rate NG tube placement as very painful, one of the most painful procedures performed in the ED, use these adjuncts whenever time and the clinical situation permit (Fig. 40-5). Spray topical vasoconstrictors, such as phenylephrine (0.5% Neo-Synephrine) or oxymetazoline (0.05% Afrin), into both nares at first in case one side proves to be problematic (see Fig. 40-4, step 2). The nares, nasopharynx, and oropharynx should all be anesthetized at least 5 minutes before the procedure. Gagging is reduced if the pharynx is anesthetized as well as the nose. Combinations of tetracaine, butyl aminobenzoate, and benzocaine (Cetacaine), nebulized or atomized (spray cans or bottles) lidocaine (4% or 10%), and lidocaine gels (2%) are most commonly used. Lidocaine preparations of 10% are most useful. Lidocaine may be nebulized and delivered by face mask with the equipment used to administer bronchodilators to asthmatics (see Fig. 40-4, step 3). This method has been found to be superior to lidocaine spray for reducing gagging and vomiting and increasing the chance of successful passage.^19,20 Cullen and coworkers concluded that nebulized nasal and pharyngeal lidocaine (4 mL of a 10% solution) reduces the discomfort associated with passage of an NG tube better than placebo does and without any lidocaine-related toxicity.²¹

Figure 40-5 Insertion of a nasogastric (NG) tube has been termed one of the most painful and unpleasant procedures performed in the emergency department, and it should not be used unless specifically indicated. Whenever possible, some form of topical anesthesia for both the nose and the pharynx should be used at least 5 minutes before passing an NG tube.

After a topical vasoconstrictor and anesthetic are administered, lubricate the tube with viscous lidocaine or lidocaine jelly.²² Lubrication and anesthesia of the nares can be facilitated by using a syringe (without needle) filled with 5 mL of an anesthetic lubricant, such as 2% lidocaine gel (Fig. 40-4, step 4). Simply putting anesthetic jelly on the tube just before insertion will not provide any anesthesia. Topical anesthetics are generally quite safe, but pay attention to the total dose of anesthetic administered to avoid toxicity.²³ Note that each milliliter of a 10% lidocaine solution contains 100 mg of lidocaine and can be absorbed systemically. In rare cases, topical benzocaine has caused methemoglobinemia even with the relatively small amounts used for endoscopy.²⁴

Although no standard exists and supportive data are sparse, some clinicians administer ondansetron (Zofran, 4 mg) or metoclopramide (Reglan, 10 mg) intravenously 5 minutes before passage of an NG tube to potentially reduce nausea and gagging and, secondarily, to improve the pain and prolongation of the procedure that gagging engenders. Metoclopramide may have additional benefits on the discomfort associated with NG tube insertion, unrelated to its antinausea effects. Ondansetron is preferred for nausea because metoclopramide can cause agitation or facial and tongue spasm, but these effects can be reversed rapidly with the administration of 25 mg diphenhydramine intravenously.

Under direct vision, not blind forcing, insert the tube gently into the naris along the floor of the nose under the inferior turbinate and not upward toward the nasal bridge (Fig. 40-6; also see Fig. 40–4, step 6). If mild resistance is felt in the posterior nasopharynx, apply gentle pressure to overcome this resistance. If significant resistance is encountered, it is better to try the other nostril because bleeding or dissection into retropharyngeal tissue may occur if force is used. Once the tube passes into the oropharynx, pause to help the patient regain composure and enhance the chance for cooperation with the rest of the procedure.

Figure 40-6 Endoscopic view of the nasal cavity before and after the application of oxymetazoline nasal spray. The nasogastric tube (NGT) is passed under the inferior turbinate, which is made more patent after the application of topical vasoconstrictors. The operator should actually look into the nose during insertion to properly guide the tube, not force it blindly. (From Thomsen T, Setnik G, eds. Procedures Consult—Emergency Medicine Module. Copyright 2008, Philadelphia, Elsevier Inc. All rights reserved.)

If the patient is alert and cooperative, a common option is to ask the patient to sip water from a straw and swallow while you advance the tube into and down the esophagus (see Fig. 40-4, step 7). This may facilitate passage of the tube. Once the tube is in the nasopharynx, flex the patient’s neck to direct the tube into the esophagus rather than the trachea. In an intubated, anesthetized, or paralyzed patient, two stacked positive pressure breaths lasting 1 to 2 seconds each via a face mask provide similar relaxation of the upper esophageal sphincter for a brief 4- to 5-second window, and this markedly increases successful tube placement.²⁵

Some gagging during the procedure is common and is not an indication to halt attempts at passage. Withdraw the tube promptly into the oropharynx if the patient has excessive choking, gagging, coughing, or a change in voice or condensation appears on the inner surface of the tube because this indicates the possibility of passage of the tube into the trachea. Inspect the tube by way of the mouth to detect coiling or respiratory passage. If the tube is lateral to the midline, this suggests correct position in the esophagus.²⁶ Once the tube is in the esophagus, advance it rapidly to the previously determined depth. Passing the tube slowly prolongs discomfort and may precipitate more gagging.¹⁷

Confirmation of Tube Placement

Before the NG tube is secured, confirm successful placement by nonradiographic means or by auscultation. Use more than one method when in doubt because all methods of confirmation have some possibility of error. Radiographic evaluation is the most definitive way to confirm the position of an NG tube, but it is not standard to routinely obtain radiographic confirmation.

A quick and simple method of confirmation is to insufflate air into the NG tube and auscultate for a rush of air over the stomach (see Fig. 40-4, step 8). If increased pressure is required to instill the air or if no sounds are heard, the tube may be malpositioned or kinked. Suspect an esophageal location if the patient immediately burps on insufflation.

If alert and cooperating, the patient will feel whether the tube is entering the trachea or lungs and can notify the inserter. Unfortunately, if the patient is comatose, struggling, or demented, the tube may pass into the lungs unrecognized. Insufflation is often insufficient to detect this type of malpositioning.³ The insufflation test is also unreliable in detecting a tube that has advanced past the stomach and into the small bowel.²⁷ In such patients, radiographic verification may be prudent.

Aspiration of stomach contents, especially if pH-tested, is more reliable and can be performed if positioning is in question. If the pH is less than 4, there is an approximately 95% chance that the tube is in the stomach and nonrespiratory placement is almost guaranteed.²⁸ Although aspirated fluid can occasionally be obtained from the lung or pleural space, the pH should be 5.5 or higher.²⁹ Approximately 4% of correctly placed tubes have aspirates with a pH higher than 5.5. Causes include duodenal reflux, antacids, H₂ blockers, or recent instillation of formula or medications.²⁹

If awake and cooperative, ask the patient to talk. If the patient cannot speak, suspect respiratory placement. Note that with small-bore tubes, patients may still be able to speak despite tracheal placement.³⁰

Once correct tube position is tentatively confirmed, secure the tube. If the patient requires abdominal or chest radiographs for other diagnostic purposes, place the NG tube before obtaining the films. An NG tube deviated to the right may occasionally be seen in patients with traumatic rupture of the aorta, but this is not a reliable indicator.

Securing the Tube

The NG tube is generally secured to the patient with tape attached to both the tube and nose (Fig. 40-4, step 10). A butterfly bandage (or tape on each side of the nose) that coils around the NG tube is a typical approach. The nose and tube should both be clean and prepared with tincture of benzoin if possible. If the tape should let go or require repositioning, both the tape and the tincture of benzoin must be replaced. It is wise to also secure the tube to the patient’s gown so that a tug on the tube will encounter this resistance before pulling on the tape securing the tube to the patient’s nose. A rubber band tied around the tube with a slipknot (Fig. 40-7) and pinned to the gown near the patient’s shoulder is effective. It is critical to ensure that the tube is secured in such a way that it does not press on the medial or lateral aspect of the nostril. Necrosis or bleeding can result if a tube is not secured correctly.

Figure 40-7 Attach the nasogastric tube to the patient’s gown with a rubber band and a safety pin so that a tug on the tube pulls the gown and not the tape holding the tube in the patient’s nose.

When a Salem sump is used, the blue pigtail must be kept above the level of the fluid in the patient’s stomach or the stomach contents may leak back through the vent lumen. If a patient needs to ambulate with a sump tube in place, fit the blue pigtail into the plastic connector at the end of the suction lumen. This creates a closed loop that should not leak.

Placement Issues

If the patient is intubated, deflate the balloon of the endotracheal (ET) tube briefly to allow passage of the NG tube. In a nonintubated unconscious patient, the NG tube is easily misplaced into the pulmonary tree. This complication may be missed during the procedure in cases in which the gag and cough reflexes are suppressed and the patient cannot talk. In addition, the absence of swallowing may prevent successful passage of the tube. In comatose or ventilated patients, several techniques have been studied to aid in passage of the NG tube. Using Magill forceps to grip the tube or stenting the end of the tube with a gum bougie passed into the most distal tube eye can help stiffen and control the tube. The combination and sequence of techniques used will depend on the clinician’s expertise, the equipment available, and the level of sedation.

If less traumatic strategies fail, an ET tube can be prepared with an ID that is slightly larger than the external diameter of the NG tube. Slit it along its lesser curvature from the proximal end to a point 3 cm from its distal end. Pass the NG tube through a naris into the oropharynx. Visualize the tip of the tube with a laryngoscope, grasp it with Magill forceps, and pull it out of the mouth. Pass the slit ET tube (generally 8 mm in ID) through the mouth into the esophagus.³¹ Alternatively, pass a 7-mm-ID slit ET tube directly through the nose into the esophagus.³² Passage into the esophagus is facilitated by the stiffness of the larger ET tube and does not require active swallowing. Thread the tip of the NG tube into the ET tube and advance it into the stomach (Fig. 40-8). Remove the slit ET tube from the esophagus. When the distal part of the ET tube is visible, slit the unslit 3-cm distal part with scissors. Remove the ET tube, and the NG tube will remain in place.³³ Advance any slack tubing with forceps or pull it back nasally, depending on the final depth required for the NG tube. The technique can also be performed by passing the slit ET tube nasally, which saves the trouble of orally advancing or nasally retracting any slack in the tubing.^33,33 Make sure that the NG tube can pass into the 7-mm-ID tube and that the ET tube is well lubricated inside and out.

Figure 40-8 Diagrammatic representation of separation of the nasogastric (NG) tube from the guiding endotracheal (ET) tube through the slit in the guiding ET tube. The NG tube has first been passed through the nose and is pulled out through the mouth. The tip of the tube is then threaded into the guiding ET tube to ensure passage down the esophagus. The guiding ET tube is removed from the esophagus before being separated from the NG tube. Note the previous placement of another ET tube in the trachea (partially shown) to avert passage of the guiding ET tube into the trachea. (Modified from Sprague DH, Carter SR. An alternate method for nasogastric tube insertion. Anesthesiology. 1980;53:436.)

In a particularly passive, intubated, sedated, unconscious, or toothless patient, guiding the NG tube with fingers into the pharynx is occasionally successful (Fig. 40-9A).³⁴ Displacing the larynx forward by manually gripping and lifting the thyroid cartilage can aid in inserting the tube,³⁵ as can simple jaw elevation. A soft nasopharyngeal airway, well lubricated, is at times easier to pass nasally than an NG tube, and then the lubricated NG tube can be passed through it. In addition, it affords some protection to the nasal mucosa if multiple attempts at passing the NG tube are necessary or if it is particularly important to minimize bleeding or trauma. Cooling an NG tube increases its rigidity, and coiling it can increase the curvature of the tube, both of which may help pass the tube. Alternatively, the NG tube and larynx can be visualized with a laryngoscope, endoscope, or the GlideScope (Fig. 40-9B).³⁵ Under laryngeal visualization, manipulation and lifting of the jaw and neck flexion can help align the tube for passage under direct vision into the esophagus.