A nasogastric (NG) tube is a flexible medical device, typically a thin, plastic tube, inserted through a patient’s nostril, passing down the pharynx and esophagus, and into the upper gastrointestinal tract. This temporary intervention is used for several reasons when a patient cannot safely eat or is experiencing certain digestive issues. Primary functions of the NG tube include administering liquid nutrition, fluids, and medications directly to the digestive system. It is also frequently utilized for gastric decompression, which involves applying suction to remove air, excess fluid, or stomach contents. This decompression is often necessary to relieve abdominal distension caused by conditions like intestinal obstruction or ileus.
Standard Termination Site and Purpose
The most common and primary termination point for a standard nasogastric tube is the stomach. The stomach is the default target because it offers a large reservoir for collecting contents or for receiving administered formulas. This placement is designed for short-term use, typically lasting only a few days to weeks.
By connecting the tube to a suction device, the stomach can be continuously emptied of gastric secretions and gas, which helps prevent nausea, vomiting, and pressure buildup. This function is particularly helpful in managing patients with bowel obstructions.
The stomach is also the site for short-term enteral feeding and medication delivery. Liquid nutrition can be delivered directly, bypassing the need for a patient to swallow safely. However, this placement is generally reserved for patients who have normal or functional gastric motility and a low risk of aspiration, as the contents can flow back up the esophagus. The ability to aspirate stomach contents also allows healthcare providers to monitor for gastrointestinal bleeding or to analyze the acid content of the stomach.
Specialized Placement Beyond the Stomach
While the stomach is the standard termination site, some patient conditions require the tube to be advanced further into the small intestine, bypassing the stomach entirely. These are generally referred to as nasoenteric tubes, with the two main types being nasoduodenal (ND) and nasojejunal (NJ) tubes. An ND tube terminates in the duodenum, the first section of the small intestine, while an NJ tube extends into the jejunum, the middle section.
This specialized post-pyloric placement is medically necessary for patients who cannot tolerate gastric feeding. Conditions such as gastroparesis, which is impaired stomach emptying, or chronic, severe vomiting necessitate this deeper placement. The primary reason for bypassing the stomach is to reduce the risk of pulmonary aspiration, where stomach contents are accidentally inhaled into the lungs.
Feeding directly into the small intestine significantly lowers this risk because the feeds bypass the stomach, which can act as a reservoir for reflux. This is often the preferred choice for critically ill patients or those with a compromised gag reflex. Although they are inserted similarly through the nose, these tubes are typically small-bore and may be placed with the aid of a guide wire or endoscope to ensure they pass the pylorus, the muscular valve at the stomach’s outlet.
Essential Confirmation Methods for Safe Placement
Confirming the precise location of the tube tip is mandatory before use, as administering anything into a misplaced tube can have severe, even fatal, consequences. The accepted gold standard for verifying the correct placement of any blindly inserted nasogastric tube is radiographic confirmation via a chest X-ray. The X-ray provides a definitive visual confirmation that the tube follows a clear path down the esophagus and terminates below the diaphragm, with no coiling or path deviation into the respiratory structures.
Although X-ray is the most accurate method, it can cause delays in treatment and exposes the patient to radiation. For ongoing verification, or as a secondary check, healthcare providers may test the pH of fluid aspirated from the tube. Gastric fluid is highly acidic, typically showing a pH value of 5.5 or lower.
In contrast, respiratory secretions are almost always alkaline, with a pH of 6 or higher. If the aspirate tests at a pH of 6 or greater, it signals that the tube may be inadvertently located in the respiratory tract. Older methods, like the auscultation of air insufflation (the “whoosh test”), are now considered unreliable and unsafe because they cannot accurately distinguish between the stomach and lung placement.
Consequences of Incorrect Tube Termination
The most serious complication from improper NG tube placement involves the tube being mistakenly advanced into the trachea or a bronchus, leading to pulmonary placement. Studies suggest that inadvertent insertion into the respiratory tract occurs in a small percentage of blind placements, but the outcomes are severe.
If fluids or feed are administered through a tube terminating in the respiratory tract, it can cause aspiration pneumonia, a serious lung infection. Other devastating consequences of pulmonary misplacement include pneumothorax, which is a collapsed lung, or pulmonary hemorrhage. The tip of the tube can sometimes puncture the lung tissue or the pleural space, leading to life-threatening conditions.
Signs of potential misplacement can include a new onset of coughing, respiratory distress, or difficulty speaking after insertion. Prompt recognition and immediate removal of the tube are necessary if any of these symptoms occur.