A nasogastric tube (NG tube) is a flexible tube inserted through the nose, down the throat, and into the stomach. This device serves as a temporary route to deliver liquid nutrition and medication directly to the stomach when a person cannot safely eat or swallow by mouth. The NG tube may also be used to remove air or stomach contents, a process known as gastric decompression or suctioning. Using the tube to administer medications requires specific preparation and a temporary clamping period to ensure the full dose is delivered and retained.
Administering Medication and Tube Flushing
The process of giving medication through an NG tube begins with meticulous hand hygiene to prevent infection. Next, the medication must be prepared, which often involves dissolving solid oral tablets or crushing them into a fine powder and mixing them with a small amount of water. However, certain medications, such as those that are enteric-coated, extended-release, or delayed-release, must never be crushed and require consultation with a pharmacist for a liquid alternative.
A crucial step before administering the medication is flushing the tube with water, typically 15 to 30 milliliters for adults, to ensure the tube is clear and patent. Once the tube is flushed, each prepared medication is administered separately, followed by a small water flush, about 5 to 10 milliliters, between each drug. This separation prevents potential drug-drug interactions and helps to clear the tube of residue.
After the final medication is delivered, a larger flush of 30 to 60 milliliters of water is administered to push all the medication completely out of the tube and into the stomach.
Standard Clamping Duration and Purpose
After the final flush, the nasogastric tube is clamped, or disconnected from suction or feeding, for a specific period to allow the medication to begin working. The standard recommended clamping duration is typically 30 to 60 minutes for most medications. This time frame is based on the general principles of pharmacokinetics, which govern how a drug is absorbed and processed by the body.
The primary purpose of clamping is to prevent the immediate loss of the drug, especially if the tube is connected to suction. If the tube were immediately unclamped and connected to suction, the medication could be withdrawn from the stomach before it has had a chance to dissolve and pass into the small intestine, where most absorption occurs.
Clamping the tube ensures the medication remains in the stomach, allowing it to dissolve and begin moving through the digestive tract. This waiting period is important because medication absorption through an NG tube can sometimes be reduced compared to traditional oral administration.
Modifying Clamping Time for Specific Medications
While 30 to 60 minutes is the common hold time, the duration can be modified based on the medication’s specific properties or the patient’s individual circumstances. Some specialized medications, such as certain viscous suspensions designed to coat the stomach lining, may require a longer contact time to be effective. In such cases, the clamping duration might be extended, sometimes up to 90 minutes, to ensure the drug has sufficient time to settle and achieve its therapeutic effect.
For patients receiving continuous tube feeding, the feeding must be paused for the entire clamping duration. This is done because the nutrients in the feeding formula can interfere with the absorption of certain medications.
If a medication is known to interact with food or requires an empty stomach for optimal absorption, the feeding may need to be held for a period before the medication is given, in addition to the post-administration clamping time. Consulting the specific instructions from a pharmacist or healthcare provider is necessary when administering complex medications to determine the exact modified clamping period.
Patient Safety and Monitoring After Unclamping
Once the prescribed clamping time has elapsed, the tube is safely unclamped and reconnected to its original function, whether that is continuous tube feeding or gastric suction. Before reconnecting, it is important to ensure the patient is positioned with the head of the bed elevated at least 30 degrees to minimize the risk of aspiration. Proper documentation of the medication administration, including the time the tube was clamped and unclamped, is a necessary final step in the procedure.
Following the procedure, the patient should be monitored for any signs of adverse reactions or discomfort. Caregivers should watch for symptoms such as nausea, vomiting, or abdominal distension, which could indicate the stomach is not tolerating the medication or that the tube may have become partially blocked.
If the tube was connected to suction, a sudden, large increase in the amount of fluid being suctioned out may indicate that the medication was not retained and was immediately withdrawn from the stomach.