A Nasogastric (NG) tube is a flexible tube that goes through the patient’s nostrils and into the oesophagus until it reaches the stomach. There are two main reasons why a patient would have an NG tube:
To administer special liquid food to patients who cannot consume food orally
To drain gastric contents (i.e. Empty the stomach)
As a nurse, you will be expected to know how to insert an NG tube, care for it once it’s in place, and administer feeds or drain gastric contents. These notes will explain the nasogastric tube insertion process. For notes about the nursing care of a nasogastric tube, you can hop to the link here.
Nasogastric Tube Insertion: Enteral Feeding
As mentioned above, there are two main reasons why a patient would need an NG tube. The NG tube is inserted for feeding purposes in patients with a functioning gastrointestinal tract who can not consume enough nutrients orally. This can happen either because they are physically unable to ingest food or are unwilling to eat.
These patients include individuals with
Chronic Medical Conditions (such as Inflammatory Bowel Disease, Hepatic Failure, Renal Failure and Respiratory Failure)
Neurological conditions (such as Cerebrovascular accident, Motor Neuron Disease, Acquired brain injury, Brain tumour or Parkinson’s disease)
Surgical treatment, including pre and post-operative management
Long-term Anorexia Nervosa
Most NG tubes are silicone or polyurethane and last up to 4-6 weeks when used for enteral feeding. The liquid food administered is a specialised combination of all the required daily nutrients and calories.
Nasogastric Tube Insertion: Gastric draining
The second reason a patient would get an NG tube inserted is to empty their upper gastrointestinal tract from any food contents, liquids and secretions. An NG drain is indicated in patients that:
Require gastric decompression during surgery or while intubated
Have bowel obstruction
Have persistent uncontrolled vomiting
Aspirated ingested toxic substances
Nasogastric Tube Insertion: The Procedure
The following text will describe the basic procedure of inserting an NG tube for educational purposes only. It assumes that the patient is conscious, responsive and alert without any limitations in their mobility. Always ensure that an experienced health professional is present during the procedure.
Start by looking through your patient’s file and identifying the indication for an NG tube insertion. Make sure that there are no contraindications documented on the patient’s file; these would include:
Abnormalities or infections in their ears, nose or throat
Oesophageal strictures, varices or abnormalities
Allergy to the lubricant or NG tube material
Perform hand hygiene and gather all the equipment required for the procedure, including:
A clean trolley
Local anaesthetic spray or jelly
pH strip and scale
Sticky tape or NG tube dressing
NG spigot (if the tube is being inserted for feeding)
NG drain bag (if the tube is being inserted for draining)
Next, determine the right size of NG tube for your patient. The tubes come in many sizes ranging from 8-18Fr. Determining the size depends on the patient’s weight and the indication. Typically smaller sizes are used in paediatrics, while the larger and thicker sizes are used in patients who require the administration of dense feeds. All tubes will have markings indicating the length, and their tip contains a radio-opaque marker that can be visible through X-rays.
Once you have selected the size of the NG tube and all your equipment is set up, you can approach the patient. Introduce yourself and explain to your patient why they need to have an NG tube inserted. Outline the procedure to the patient and relatives and allow time to address concerns or questions before starting. It’s essential to gain verbal consent before proceeding with the NG insertion.
After having the patient’s consent, you can initiate the procedure by estimating how much of the NG tube you need to insert to reach the patient’s stomach. Ask the patient to sit comfortably upright with their back and feet supported.
Apply hand hygiene, and then with the NG tube still in its wrapper, place the tip of the NG tube at the tip of the patient’s nose. Keep the tip secure, and pass the rest of the tube behind the patient’s ear, tracing your fingers down to the centre of the patient’s abdomen. Your fingers should land between the patient’s xiphoid and the umbilicus, as this indicates the location of your patient’s stomach. With the tube still in hand, take note of the mark closest to your finger, as this number gives you an estimate of how much NG tube you need to insert.
Because your hand was in close contact with the patient, you should re-apply an alcohol-based hand rub and put on your non-sterile gloves once dry. Open up the NG tube packaging carefully and allow the tube to rest on the bottom wrapper. Squeeze the lubricant at the tip of the NG tube and move it upwards. (Remember that if the lubricant contains an anaesthetic gel, you will need to ask for a prescription before the procedure).
Select the wider nostril and gently slide the NG tube against the floor of the nasal cavity, pointing towards the septum. Your patient will likely gag when the tip of the NG tube reaches the pharynx, and when this happens, you should instruct them to swallow their saliva. If your patient does not manage to swallow, you can allow them to drink a small amount of water to trigger the swallowing reflex.
This action will open up the pharynx allowing the tube to enter the oesophagus. Continue to gently thread the tube inwards until you reach the estimated mark, press the spigot to close the NG tube and use the adhesive dressing to secure it in place. The next step is to confirm the tube’s position.
Place a pH strip into the kidney dish, replace the spigot with the 60ml syringe and aspirate a few millilitres. If the NG tube is in the stomach, gastric fluid is aspirated into the syringe. Replace the syringe with the spigot again, and press the gastric juice over the pH strip in the kidney dish. The pH strip changes colour within a few seconds, and by comparing it to the pH scale, you’ll be able to determine the pH level of the contents. A pH of 5.5 or lower is accepted as proof that the aspirated fluid was from the stomach, which means that the tube is in the right place. If the pH level is higher than 5.5, check whether the patient has taken anything that may increase the gastric pH, such as milk, proton pump inhibitors or H2 receptor antagonists.
Once the position is confirmed, use the measuring tape to measure the length of the NG tube from the tip of the patient’s nose to the end. Following that, you can remove your gloves, apply an alcohol-based hand rub and document the procedure on your patient’s file. Make sure to record the date and time of insertion, the size and material of the NG tube, the pH level of gastric contents and the length of the remaining NG tube.
If the NG tube is indicated for feeding regimens, the patient will likely need an X-ray to confirm its position. The tip of the tube can be seen as a white radio-opaque line underneath the diaphragm and pointing towards the left side of the abdomen.
The next steps following an NG Tube Insertion depend on the patient’s specific plan, if the NG was inserted for to drain the stomach from gastric contents then a drain bag will need to be attached and secured safely. On the other hand if the NG was inserted for feeding then you’ll need to follow the NG Feeding Procedure according to the prescribed regimen.