A nasogastric (NG) tube is a thin, flexible plastic conduit inserted for temporary medical access to the stomach. Its pathway runs from the nasal cavity directly into the stomach. This device provides a temporary and non-surgical way to deliver or remove substances, serving as a direct connection to the upper gastrointestinal tract. It is typically employed in hospital settings for patients who require gastric access for various short-term treatments.
Anatomy and Placement of the Tube
The NG tube follows a specific anatomical route beginning at the nostril, passing through the nasal cavity, and entering the pharynx. It navigates the nasopharynx and oropharynx before descending into the esophagus, which connects the throat to the stomach. The tube finally comes to rest inside the stomach.
Inserting the tube is performed by a trained healthcare professional, starting with measuring the length needed from the nose to the earlobe and then down to the xiphoid process (the base of the sternum). The tube’s tip is lubricated to ease passage. During insertion, the patient is often asked to swallow water or tuck their chin toward their chest to help guide the tube past the trachea and into the esophagus.
Once the tube is in place, its position must be verified before any use to prevent severe complications like feeding into the lungs. The most reliable confirmation method is a chest X-ray, although testing the pH of aspirated gastric contents provides a quick indication of correct placement. Gastric fluid is highly acidic (pH between 0 and 5), confirming the tube’s location within the stomach. The tube is then secured externally to the nose using tape or a fixation device to prevent accidental displacement.
Nutritional Support and Medication Administration
One primary function of an NG tube is to provide enteral nutrition, delivering specialized liquid food directly into the stomach for patients unable to eat or swallow safely. This is frequently necessary for individuals recovering from a stroke, those with severe head or neck cancers, or patients with altered levels of consciousness who are at risk of aspiration. The nutritional formulas are carefully calculated by dietitians to contain macronutrients, vitamins, and minerals required for healing and maintaining a healthy weight.
The liquid feed can be administered continuously over many hours using a pump, or in scheduled amounts called bolus feedings, often given via a large syringe. The use of the gastrointestinal tract for feeding helps maintain the health and normal function of the gut, which is preferable to intravenous methods when possible.
NG tubes also serve as a safe channel for administering liquid medications or tablets that have been safely crushed and dissolved in water. To ensure the full dose of medication or formula is delivered, the tube must be flushed with water before and after each administration. This flushing action is also necessary between different medications to prevent chemical interactions or clogging of the tube.
Gastric Decompression and Suction
The second main purpose of the NG tube is to empty the stomach, a process known as gastric decompression or suctioning. This is achieved by connecting the external end of the tube to a low-level suction device to remove excess air, fluid, and stomach contents. Decompression is often performed to relieve abdominal pressure and distension caused by conditions like a small bowel obstruction or a post-operative ileus, where normal intestinal movement is temporarily interrupted.
Many decompression tubes, such as the widely used Salem Sump, are designed with two separate channels or lumens. The wider channel is used for suctioning gastric contents, while the smaller second channel acts as an air vent, or sump. This air vent prevents the tube from creating a vacuum and adhering to the stomach lining, which could cause irritation or damage to the mucosa.
Suction is typically maintained at a low, intermittent setting to minimize the risk of trauma to the stomach wall. Beyond routine decompression, the tube can be used for gastric lavage, which involves washing out the stomach contents, sometimes in emergency situations involving the ingestion of toxins or a severe upper gastrointestinal bleed. By removing fluids and gas, this function helps prevent vomiting and aspiration.
Patient Care and Potential Complications
Living with an NG tube requires consistent daily care focused on both the tube’s function and patient comfort. Since the tube occupies one nostril, meticulous hygiene is required, including gently cleaning the skin around the nose where the tube is secured to prevent skin irritation or pressure ulcers. The securement tape should be checked and often changed daily, sometimes alternating nostrils to avoid constant pressure on one site.
Aspiration, the entry of stomach contents into the lungs, is one of the most serious risks associated with an NG tube, particularly if the tube is misplaced or becomes clogged. To mitigate this, patients receiving tube feeds must remain positioned with the head of the bed elevated at least 30 degrees during and after feeding. The constant presence of the tube can also lead to minor complications like nasal irritation, sinusitis, or occasional nosebleeds (epistaxis).
Tube clogging is a common mechanical issue, often resulting from insufficient flushing or improperly prepared medications. Regular flushing with water helps maintain the tube’s patency and effectiveness. The NG tube is generally a temporary measure, and it is removed once the underlying medical issue resolves, such as the return of normal swallowing function or the clearance of a bowel obstruction.