Nasogastric (NG) tubes are medical devices placed through the nostril, down the esophagus, and into the digestive tract. They serve various temporary medical purposes, providing a pathway for substances to enter or exit the body. The specific placement of an NG tube depends on its intended function.
Termination in the Stomach
The most frequent termination point for a nasogastric tube is the stomach. One primary reason for stomach placement is gastric decompression, which involves removing air or fluid from the stomach to relieve pressure, often necessary in cases of bowel obstruction or after surgery.
Another common use for an NG tube ending in the stomach is for administering medications. The stomach provides a convenient entry point for liquid medications or crushed pills mixed with water to be delivered directly into the digestive system, bypassing the need for oral intake.
Short-term enteral feeding is also facilitated by stomach placement, allowing liquid nutrition to be delivered when a person cannot eat adequately by mouth. Gastric lavage, a process of washing out the stomach, is also performed with tubes terminating in this area, for example, in cases of poisoning or gastrointestinal bleeding.
Termination Beyond the Stomach
In some medical scenarios, a nasogastric tube may extend beyond the stomach into the small intestine, specifically the duodenum or jejunum. When the tube passes the pyloric sphincter and enters the small bowel, it is often referred to as a nasoenteric tube, though it originates nasally like an NG tube.
This post-pyloric placement is chosen when the stomach needs to be bypassed or when there is concern about the stomach’s ability to tolerate substances. Reasons for placing a tube beyond the stomach include conditions like gastroparesis, where the stomach empties slowly, or in individuals at high risk of aspirating stomach contents into their lungs.
Delivering nutrition directly into the small intestine can also be beneficial in cases of severe pancreatitis or after certain types of gastric surgery. This approach ensures that nutrients are delivered to a part of the digestive tract that can absorb them effectively, even when the stomach’s normal function is impaired.
Confirming Correct Placement
Ensuring the correct termination of a nasogastric tube is an important step for patient safety and treatment effectiveness. Healthcare professionals employ several methods to verify the tube’s position within the body. The gold standard for confirming accurate placement is a chest X-ray, which provides a clear visual image of the tube’s path and its exact location in relation to anatomical landmarks.
Beyond X-ray confirmation, bedside methods are also used, though they are not definitive on their own. One common method involves aspirating a small amount of fluid from the tube and testing its pH level. Gastric fluid is acidic, with a pH ranging from 1.0 to 5.5, due to the presence of hydrochloric acid in the stomach. Conversely, fluid from the respiratory tract or intestines has a higher, more alkaline pH.
Visual assessment of the aspirated fluid can also provide clues about the tube’s location. Gastric aspirate may appear clear, grassy green, or tawny, while intestinal aspirate can be bile-stained, appearing yellowish or greenish-brown. These verification steps are important to prevent complications, such as the tube being accidentally inserted into the lungs, which could lead to respiratory issues.