A nasogastric (NG) tube is a slender, flexible medical device inserted through the nasal passage, down the throat, and into the stomach. This temporary access is used for patients who cannot safely ingest food or medication orally, or who require stomach drainage. The purpose of the tube is to deliver nutrition and medicine, or to decompress the stomach by removing air and fluid. Accurately inserting and confirming the placement of an NG tube is a fundamental nursing skill, as improper positioning can lead to serious complications such as aspiration pneumonia.
Pre-Procedure Preparation and Assessment
Before attempting the insertion, a thorough patient assessment is necessary to identify any contraindications. The nurse must check for a gag reflex, which indicates the patient’s ability to protect their airway, as well as a history of facial trauma, recent nasal or esophageal surgery, or coagulation issues. Contraindications such as severe maxillofacial trauma or basilar skull fractures prevent nasal insertion due to the risk of tube misdirection into the brain cavity.
Gathering the correct equipment is a crucial step that prepares the field for a smooth insertion process. This typically includes the appropriate size of NG tube, water-soluble lubricant, an enteral syringe, pH indicator strips, a securing device or tape, gloves, and an apron. Tube sizes vary, but small-bore tubes (6 to 12 French) are generally preferred for feeding due to increased patient comfort and reduced risk of certain complications.
The patient must be educated about the procedure and positioned correctly to facilitate the tube’s passage. Ideally, the patient should be placed in a high Fowler’s position, sitting upright with the head supported and the neck slightly flexed. This posture helps straighten the path from the pharynx to the esophagus and encourages the necessary chin-tuck maneuver during insertion.
A precise measurement must be taken to estimate the length of the tube required to reach the stomach. The most common external method is the Nose-Earlobe-Xiphoid (NEX) technique. This involves measuring the distance from the tip of the patient’s nose to the earlobe, and then from the earlobe down to the xiphoid process (the bottom tip of the sternum).
The NEX measurement provides a baseline for the approximate depth of insertion, and the length should be marked on the tube with a piece of tape or noted using the centimeter markings already printed on the tube. Some current evidence suggests the traditional NEX measurement may be too short to reliably place the tip securely in the stomach. Newer guidelines often recommend adding an additional 10 centimeters to the NEX length to ensure the tube tip passes beyond the gastro-esophageal junction and into the gastric body.
Step-by-Step Insertion Technique
Once the measurement is marked and the patient is positioned, the distal tip of the NG tube should be lubricated with a water-based gel to ease its passage. The nurse selects the nostril that appears most patent, often by asking the patient to occlude one side and gently sniff through the other. The tube is advanced posteriorly, parallel to the nasal floor and aiming back, not up, to avoid damaging the nasal turbinates.
As the tube reaches the nasopharynx, typically 10 to 20 centimeters into the passage, resistance is often encountered. At this point, the patient is instructed to tuck their chin toward their chest, which helps close the opening to the trachea. This chin-tuck maneuver directs the tube toward the esophagus rather than the airway.
The patient should be encouraged to take small sips of water and swallow continuously as the tube is advanced past the pharynx. The act of swallowing causes the epiglottis to cover the glottis, temporarily closing the airway and facilitating the tube’s entry into the esophagus. Advancing the tube only during the swallow reflex improves the likelihood of successful placement.
If the patient begins to cough, choke, or show signs of respiratory distress, or if the tube meets significant resistance, the insertion must be immediately halted and the tube pulled back slightly. This reaction suggests the tube may have entered the trachea, and reattempting the insertion after allowing the patient to rest and recover is necessary. The nurse should also check the patient’s mouth to ensure the tube has not coiled in the back of the throat.
The tube is continually advanced until the pre-marked length reaches the nostril. Once the full length is inserted, the tube is temporarily secured to the patient’s nose with a small piece of hypoallergenic tape. This temporary securing prevents accidental dislodgement while the definitive placement is verified.
Verification of Tube Placement
Confirming the tube’s location is the most important step to prevent lethal complications like pulmonary aspiration. The gold standard for initial placement confirmation is a chest X-ray. A properly obtained and interpreted radiograph is the only method that definitively visualizes the tube’s entire path and confirms the tip is positioned in the stomach, typically below the diaphragm.
Bedside methods are often used for ongoing verification, with pH testing being the most common alternative. This involves aspirating a small amount of fluid from the tube using an enteral syringe and testing it with specialized pH paper. A pH reading of 5.5 or lower strongly indicates the tube is located in the acidic environment of the stomach.
If the tube is positioned in the respiratory tract, the aspirate will typically have a higher, more alkaline pH, often greater than 6. The visual appearance of the aspirate can also offer a clue. Gastric fluid is usually clear, grassy green, or yellow-tinged, while respiratory secretions are generally clear and thin.
Medications that suppress stomach acid, such as proton pump inhibitors, can increase the gastric pH and make this test less reliable. This requires greater reliance on X-ray confirmation.
It is essential to understand that the traditional auscultation method, often called the “whoosh test,” is widely discouraged and considered unreliable by current guidelines. This technique involves injecting air into the tube while listening for a whooshing sound over the stomach with a stethoscope. Research has shown that a similar sound can be heard even when the tube is misplaced in the lungs, leading to a high rate of false-positive results.
Post-Insertion Care and Documentation
Once the correct placement is confirmed, the tube must be secured definitively to prevent migration or accidental removal. A commercial fixation device or a secure taping method should be used to anchor the tube firmly to the nose and cheek. The exact length of the tube visible from the nostril should be measured and recorded to serve as a baseline for all future checks.
The patient’s head of the bed must be elevated to at least 30 to 45 degrees, especially during continuous feeding and for a period afterward. This minimizes the risk of reflux and aspiration. Regular flushing of the tube with water is necessary to maintain patency and prevent clogging, and should be done before and after administering feeds or medications.
The insertion site should be monitored daily for signs of skin breakdown or pressure injury around the nostril. Monitoring for potential complications is an ongoing responsibility, including watching for signs of respiratory distress, coughing, or vomiting, which could indicate a dislodged tube. Any change in the external length of the tube or a new onset of respiratory symptoms requires immediate re-verification of the tube’s position. Complete documentation is mandatory, recording the tube size, the selected nostril, the measured insertion length, the method used for placement confirmation, and the patient’s tolerance of the procedure.