A nasogastric (NG) tube is a flexible, hollow tube inserted through a person’s nostril, guided down the esophagus, and into the stomach. This medical device delivers liquid nutrition or medications directly into the stomach, or removes stomach contents. Ensuring correct placement is a fundamental safety measure before its use.
Importance of Correct Placement
Correct NG tube placement is paramount, as misplacement can lead to severe, life-threatening complications. If inserted into the respiratory tract (trachea or bronchus) instead of the esophagus, administering fluids or medications can cause aspiration pneumonia. This dangerous lung infection results from foreign material entering the airways.
Misplacement can also lead to acute respiratory distress by obstructing the airway. An improperly placed tube fails to deliver intended nutrition or medication, compromising patient health and treatment effectiveness. Confirming the tube’s position within the stomach is a non-negotiable step to prevent harm and ensure therapeutic benefit.
Primary Verification Methods
Verifying NG tube placement relies on several reliable methods, often used in combination for comprehensive assurance. These techniques help prevent the significant risks associated with misplacement.
X-ray confirmation is widely considered the most definitive method. An X-ray provides a clear visual image of the tube’s entire path, from the nostril down to its tip, which should be visible within the stomach. This method is typically performed immediately after initial insertion, before any substance is administered.
pH testing of aspirate is a common and reliable method for ongoing verification or routine checks. This involves gently withdrawing a small amount of fluid from the NG tube using a syringe. The pH of this aspirated fluid is then tested using pH indicator paper or a pH meter. Gastric fluid typically has a highly acidic pH, usually 5.5 or less, due to the presence of hydrochloric acid in the stomach.
Respiratory secretions tend to have a pH of 6.0 or higher, while intestinal fluid might range from 6.0 to 7.0. Therefore, an aspirate with a pH of 5.5 or below strongly indicates the tube’s tip is in the stomach. Visual inspection of the aspirate can offer supporting information, though it is not a definitive verification method on its own. Gastric fluid can appear clear, grassy green, tan, off-white, or brown.
Respiratory secretions are typically clear, colorless, or yellowish, and may contain mucus. While appearance can be indicative, color alone is not a reliable differentiator, as some gastric fluids might mimic respiratory secretions.
Another supporting method involves measuring the external length of the tube from the nostril to its entry point. During insertion, the tube is marked at the nostril, and this measurement is recorded. Consistently checking this mark helps determine if the tube has migrated. This method indicates tube migration rather than confirming initial internal placement, so it must always be used with other primary verification techniques.
Less Reliable Verification Methods
Certain methods for NG tube placement verification are now considered unreliable and should be avoided. Relying on these techniques can provide false assurance, potentially leading to serious patient harm.
One such method is auscultation, or the “air bolus” method. This involves injecting a small amount of air into the NG tube while listening over the stomach area with a stethoscope for a “whooshing” sound. While historically believed to confirm gastric placement, research shows a similar sound can be heard if the tube is in the esophagus or respiratory tract. Using auscultation alone can lead to false security and administration of substances into the lungs.
Another unreliable method involves placing the open end of the NG tube into a cup of water to observe for bubbles. Continuous bubbling was thought to indicate airway placement, and absence of bubbles, gastric placement. This method is unreliable because bubbles can occur from residual air or stomach gas, even with correct placement. Conversely, no bubbles do not guarantee gastric placement, as the tube could still be in the esophagus or a main bronchus.
What to Do If Misplacement is Suspected
If NG tube misplacement is suspected, immediate action is necessary for patient safety.
First, immediately stop all infusions (liquid nutrition, water, or medications) through the tube. Continuing infusions into a misplaced tube can lead to severe complications, particularly if it’s in the respiratory tract.
Next, notify a healthcare professional, such as a registered nurse or a physician, without delay. These professionals have the training and authority to assess the situation and determine the appropriate course of action. Individuals who are not trained healthcare professionals should avoid attempting to re-insert, reposition, or remove the tube themselves. Only qualified personnel should perform these actions, as improper manipulation can cause further injury or complicate the situation. While awaiting professional assistance, observe the patient for any signs of respiratory distress, such as coughing, choking, difficulty breathing, or changes in skin color, which could indicate pulmonary aspiration.