Access and Intubation of the Stomach and Small Intestine

Nasogastric and Nasoenteric Intubation

GI intubation is a well-established diagnostic and therapeutic modality with a long record of experience. Early descriptions of nasogastric tubes and intestinal intubation date from the 17th century. Modern tubes are known eponymously for the individual who introduced them into clinical practice. In 1921, Levin described a single lumen catheter fenestrated at the distal end for decompression with low intermittent suction or gravity drainage, or feeding. A modification of the Levin tube is now widely used and known as a Salem sump . The Salem sump tube has a second lumen that permits air to be withdrawn into the stomach, or sump, during suctioning, thereby avoiding adherence of the tube to the gastric mucosa, and possible injury. This tube is used most commonly today for GI decompression in the setting of gastroparesis, mechanical bowel obstruction, or functional inertia of the bowel or ileus.

In 1934, Miller and Abbott first introduced a long, balloon-tipped intestinal tube designed to pass into the intestine via gentle advancement and peristalsis; subsequent modifications included percutaneous, weighted, multilumen, and silicone models. Temporary placement of a long tube into the small intestine for decompression was described by White in 1956 and was later popularized by Baker, who devised his own eponymous tube. Generally, long tubes have weighted or balloon-tipped ends and are intended to pass distally to provide intestinal or gastric decompression.

Nasoenteric tubes designed for feeding are similar to long tubes and are intended to traverse the pylorus, but unlike decompressive tubes, they are generally of smaller caliber and made of softer materials than standard sump or long tubes. These tubes often require a stiffening stylus for passage and manipulation. The most widely used of these tubes, introduced by Dobbie and Hoffmeister in the 1970s, is now recognized as the Dobbhoff tube . The tip of this tube is slightly larger and heavier than the remainder of the catheter, which may or may not facilitate passage with the pylorus. Unassisted bedside placement into a postpyloric position can be simple, and a multitude of methodologies have been suggested. Promotility agents, patient positioning, insufflation of air, and other methods have been advocated to assist with advancement into a postpyloric position, but results are mixed. Endoscopic, radiologic, magnetic, and electromagnetic methods have been described, and will be discussed later.

Indications

Obstruction and the need for decompression are the most common indications for nasogastric and nasoenteric intubation. Less commonly, intubation of the stomach or small intestine is used for diagnostic or therapeutic means, including gastric lavage and evacuation of gastric contents in the initial management of upper GI bleeding or toxic ingestion. Diagnostic uses are numerous and include aspiration to determine the presence of drugs or toxins, measurement of gastric secretions, volume of output, or pH, and for the procurement of specimens for culture of Mycobacterium or Helicobacter pylori . Therapeutic uses for gastric and enteral intubation are well defined. Decompression of air or enteric contents is very common, and is often used in the setting of ileus, mechanical bowel obstruction, gastric dilation, perioperative gastric drainage, or reduction of aspiration risk in select patients. The routine use of postoperative nasogastric decompression after abdominal surgery has fallen out of favor. The evidence does suggest that selective use in patients with the indications listed earlier, including chronic nausea and vomiting, is associated with more frequent pulmonary complications than routine postoperative tube decompression. Decompression is integral to the management of intestinal obstruction; it relieves any advancement of fluid or gas from the stomach and can be used to determine improvement because the volume of output will decrease if the obstruction improves.

In terms of decompressive treatment of intestinal obstruction, nasogastric decompression was often sufficient to relieve the obstruction from the influx of air and fluid. In the case of partial intestinal obstruction, decompression may effect relief of obstruction within 48 hours. Persistent obstructions will warrant further diagnostic investigation and possible operative management. In patients with suspected complete intestinal obstruction, nasogastric intubation is important in the preoperative resuscitative period to decompress the stomach and minimize aspiration, but surgical management remains the mainstay of therapy.

Intraluminal plication of at-risk bowel following extensive adhesiolysis using a long tube (Baker, Cantor, others) has been described and evaluated in the literature. Although the technique is encouraged by some, it has gradually fallen out of favor because complications associated with an enterostomy-placed Baker tube are prohibitive. Nasally introduced tubes have been suggested as having efficacy in decompression of partially obstructed bowel, but the results are mixed. However, without gastric decompression, symptomatic relief from nausea and/or emesis may not be achieved. One randomized control study comparing short and long decompressive tubes demonstrated no advantage. Although others have described long tubes as a secondary treatment and have anecdotally noted value in this legacy therapy, most have abandoned it.

Contraindications

Soft feeding tubes (Dobbhoff, Keofeed, Cortrak and similar tubes) are smaller bore and useful for gastric or postpyloric feeding and may be placed at bedside transnasally. Nasoenteric access is a simple, useful, and reasonably comfortable means of enteral access when desired in patients with indications. Contraindications to nasoenteral access include nasopharyngeal obstruction, esophageal obstruction or perforation, recent foregut manipulation or surgery, and craniofacial trauma. While orogastric intubation is the preferred route for access in the presence of craniofacial trauma, it may not be practical in the patient without a secured airway. Coagulopathy is also an important contraindication when intubation is placed for nonurgent purposes to avoid epistaxis or other bleeding.

Methods of Bedside Intubation

Nasoenteric intubation is easily done at the bedside, but despite the simplicity of the procedure, it can have several pitfalls leading to complications. Patients vary in their level of cooperation, alertness, and cognitive capacity. Consent should be obtained according to institutional requirements, and should include an assessment of benefits, risks, and experience.

For patients who are awake, alert, and cooperative, Fowler position is helpful with a 90- degree angle preferred. A chair may be used, but a stretcher or bed may provide better patient comfort. The patient's neck should be slightly flexed to avoid endotracheal placement. The patient should be in a quiet room because distractions can be problematic. The patient should understand the reason for the procedure, the steps involved, and be prepared for the uncomfortable nature of nasogastric intubation. Parenteral anxiolytic and analgesic agents are usually not necessary, and can complicate appropriate passage.

Assessment for nasal passage patency is important, especially in a patient with a history of septum abnormality. An emesis basin and protective barrier (towel, drape) may be helpful to the patient. Inhalation through the nose with each nostril sequentially obstructed can help decide which passage to use.

The tube should be warmed by sliding it repeatedly through gloved hands to soften the structure and create a slight curve in the tube. Most tubes are marked with centimeter indicators to identify the length of the indwelling section, but some may be unlabeled. The correct distance of insertion should be about 50 cm for intragastric placement, and usually more than 65 cm for postpyloric placement.

Prior to insertion, a water-based lubricant with or without local topical anesthetic (2% lidocaine, viscous) should be applied to the tube and to the nasal passages. Anesthetic sprays (benzocaine, butamben) may also be used, but will not offer any lubrication.

The tube is inserted into the nostril with a trajectory toward the posterior nasopharynx, parallel to the patient's ipsilateral angle of the jaw or pinnae. The tube should not be inserted in the cephalad direction because this will result in the tube curling in the nasopharynx or trauma to the nasal mucosa. Maintaining the tube along the floor of the nasal passage may facilitate entry into the posterior pharynx. As the tube reaches the posterior nasopharynx and some mild resistance is met, gentle pressure will facilitate the tip of the tube turning caudally to descend into the oropharynx.

The patient may be given a cup of water with a straw and permitted to sip steadily and swallow water (once the tube is inserted and the first resistance is met), which facilitates closing the epiglottis and allowing directed passage into the upper esophagus. Patients who experience severe pain, gagging, anxiety coughing, respiratory distress, or significant resistance noted by the inserter should be permitted respite before subsequent attempts are made. Gagging, coughing, or other respiratory distress may be signs of laryngeal passage and should prompt the provider to remove the tube and restart.

Once passage into the esophagus is successful, the tube should continue to advance until the desired depth is reached. Once in the stomach, at about 50 to 55 cm, the tube's position should be assessed. Confirmation of tube placement should be accomplished prior to using the tube for any indication, and many methods have been described.

Insufflation with auscultation alone is an unreliable technique, and although it may be helpful in the distal tube position for some providers, it should not be the only method used to confirm location. Aspiration of enteric or gastric material may also offer confidence in some settings, but the tube contents are unclear during passage and there is no proof of tip location. Radiographic evidence remains the mainstay for tip location confirmation and should be performed routinely after intubation. Contrast may be required in some settings to determine the course of the tube, and thinned solutions of barium are likely the least expensive and simplest to use. Devices currently exist that use electromagnetic sensors at the tube tip (Cortrak, CORPAK MedSystems, Buffalo Grove, Illinois), and have been reviewed ( Fig. 58.2 ). Retrospective and prospective studies exist demonstrating reliable use of an active positioning detection system to follow the tube as it is passed by the provider. Systems using real-time imaging to provide gastric or small bowel intubation are useful bedside adjuvants to the provider, and provide a level of confidence. Resistance, patient symptoms, and training of personnel should be considered when deciding how best to confirm location. In experienced hands, electromagnetic detection is useful and provides cost savings with respect to radiographic imaging, but is not yet the gold standard. Placement in the respiratory system occurred in up to 3.2% of patients in one study, and pneumothorax occurred in up to 1.2%, with an associated mortality. These authors advocate a simple multimodality method for confirmation, including an experienced procedurist, accurate reporting regarding ease of passage, patient symptoms and signs, and the use of routine electromagnetic detection with selective radiographic imaging or with routine radiographic imaging. The risk of pneumothorax, intrapleural placement (and subsequent administration of nutrition), or other complications, although low, has dramatic and morbid complications that should be regarded as “never events” in the realm of patient safety.