Nasogastric and Feeding Tube Placement

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, blocking future tube function and potentially causing 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 an 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. The most commonly used size is 16 Fr, although larger and smaller sizes are available.

The major indication for NG tube placement and suction is to aspirate the stomach contents in patients with gastric bleeding, 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. 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. Patients passing clots or blood per rectum or those with known previous lower GI bleeding are usually experiencing lower GI bleeding. Except when frankly bloody fluid is obtained, an NG 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. NG tubes prolong the hospital stay, pain, and hyperamylasemia in those with mild to moderate pancreatitis. 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 an 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. Severe coagulopathy is a relative contraindication to passage of an NG tube. In patients with a coagulopathy or significant facial or head trauma, passing the desired tube 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. Aspiration is also quite common with nasoenteral feedings in debilitated patients, hence the use of a gastrostomy feeding tube for this condition. An NG tube should be avoided when possible in patients who have undergone gastric bypass surgery or lap banding procedures.

Extended irrigation of the stomach with water in a patient with upper GI hemorrhage can lower serum potassium levels, and animal studies suggest that cold water lavage can cause rather than control bleeding. No study has shown irrigation to be effective in the control of bleeding, and vigorous lavage with cold water may lower the body temperature. Erythromycin has been demonstrated to be effective in clearing the stomach for endoscopy, 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-mL 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

Most NG tubes are placed at the bedside in an awake patient. 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. 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 ). 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 whilst first one and then the other nostril is occluded. Pass the tube down the more patent naris.

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 [Hospira Inc., Lake Forest, IL]) or oxymetazoline (0.05% Afrin [Bayer Healthcare LLC, Whippany, NJ]), 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 [Cetylite Inc., Pennsauken, NJ]), 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. 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 and without any lidocaine-related toxicity.

After a topical vasoconstrictor and anesthetic are administered, lubricate the tube with viscous lidocaine or lidocaine jelly. 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 (see 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. 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.

Although no standard exists and supportive data are sparse, some clinicians administer ondansetron (Zofran [GlaxoSmithKline, Research Triangle Park, NC], 4 mg) or metoclopramide (Reglan [Baxter Healthcare Corp., Deerfield, IL], 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.

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.

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, 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. With the mouth open, inspect the tube in the posterior pharynx to detect coiling or respiratory passage. If the tube is lateral to the midline, this suggests correct position in the esophagus. 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.

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. Radiographs may be more useful in the obtunded patient. Alert and cooperative patients will feel when a tube is entering the trachea or lungs and will be very symptomatic and therefore obviously alert the clinician. Patients who are struggling or have altered sensorium may not give any sign when the tube passes into the lungs, and therefore careful confirmation of placement, usually with radiography, is critical for these individuals. Ultrasound, when successful, is also highly reliable (see Ultrasound Box 40.1 ).

Ultrasound Box 40.1: Assistance in Nasogastric Tube Placement

Ultrasound has emerged as a new modality to assist in placement verification of nasogastric tubes, both during the procedure and as a confirmatory test after the procedure.

Place the high-frequency transducer on the patient's neck transversely between the cricoid cartilage and the suprasternal notch, slightly off to the side with the orientation button to the patients' left. ( Fig. 40.US1 ). Obtaining a clear view of the esophagus sometimes involves slight angling of the probe and occasionally even benefits from some minor tracheal manipulation, usually leftward displacement. With these maneuvers, it is probably possible to visualize the esophagus over 90% of the time. ( Fig. 40.US2 )

When the nasogastric tube passes the probe image level, the esophagus acquires a bright echogenic density with posterior shadowing ( Fig. 40.US3 ). The nasogastric tube's strong interaction with the ultrasound may obscure clear visualization of the esophageal wall. A brighter echogenic density is obtained if there is a metal guidewire in the tube, as is common in feeding tubes but not in Salem sump tubes.

If 20 cm of tube has been passed but the esophageal appearance hasn't changed, the tube is likely in the trachea or coiled in the mouth and failing to pass. Sometimes the empty esophagus isn't easily seen, and then it becomes even more important to distinguish the course of the tube and ensure that the tube is in an extratracheal soft tissue space and not in the trachea. A lateral cross-sectional view with the probe pointed across from the side (by sliding the probe around the neck from the original transverse position, as shown in Fig. 40.US4 ) or oblique angles of the probe may allow the nasogastric tube to be visualized as being clearly outside the trachea.

Confirmation of tube placement in the stomach is less reliable, even after successful placement. Place the low-frequency probe over the epigastric area and try to visualize the tube. Fluid can be injected through the tube, creating a visible “foggy” disturbance in the stomach. Such confirmation reliably indicates proper placement, but when absent does not imply the tube must be replaced; rather, alternative confirmatory measures should be employed prior to using the tube for instillation of materials. Visualization of the nasogastric tube in the epigastrium on still shots is possible ( Fig. 40.US5 ). Note that still views of the nasogastric tube in the epigastric region can look similar if the tip is in the stomach, distal esophagus, or proximal duodenum.

A quick, simple, but unreliable 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. Left pulmonary tubes and tubes which have advanced past the stomach into the small bowel often sound so similar to properly placed tubes that misplacements are not detected.

Aspiration of stomach contents, especially if pH-tested, is more reliable and can be performed if the tube position 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. Although aspirated fluid can occasionally be obtained from the lung or pleural space, the pH should be 5.5 or higher. Approximately 4% of correctly placed tubes have aspirates with a pH higher than 5.5. Causes include duodenal reflux, antacids, H ₂ blockers, or recent instillation of formula or medications.

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.

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 (see Fig. 40.4 , step 10 ). Excellent purpose-made tape NG holders exist. A butterfly bandage (or tape on each side of the nose) that coils around the NG tube is a typical approach. Clean and prepare the nose and tube with tincture of benzoin if possible. If the tape lets go or requires repositioning, replace both the tape and the tincture of benzoin. 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.

When a Salem sump is used, keep the blue pigtail 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.