Nasogastric tube insertion is a medical procedure in which a plastic tube ( nasogastric tube or NG tube or Ryle’s tube) is inserted into the stomach via the nose. This procedure provides access to the stomach and its contents for diagnostic and therapeutic purposes.
Indications for Nasogastric Tube Insertion
A nasogastric tube provides access to the stomach. This helps to drain gastric contents, decompress the stomach, obtain a specimen of the gastric contents, or introduce a passage into the gastointestinal tract.
Main indications include:
- Gastric lavage in cases of drug overdosage or poisoning.
- Following ingestion of corrosive substance, nasogastric tube can be kept to prevent stricture formation and for the development of a tract in the esophagus that later can be used for balloon dilatation.
- Feeding an unconscious patient or patient with bulbar (cranial nerves) palsy having dysphagia.
- To prevent vomiting and aspiration, as well as to assess gastro-intestinal bleeding in trauma patients.
- For gastro-intestinal decompression as with paralytic ileus, intestinal obstruction or post-operative after laprotomy.
- To analyse gastric contents.
Procedure of Nasogastric Tube Insertion
Before starting the procedure, the nose must be examined. If there is deviated nasal septum, the wider nostril is selected. In case of discharge, the cleaner nostril is selected. To determine which nostril is more patent, the patient is asked to occlude each nostril one by one and breathe through the other.
With the patient’s head tilted backwards, instill 10 mL of local anaesthetic (lidocaine 2%) down the more patent nostril. The patient is asked to sniff and swallow to anesthetize the nasal and oropharyngeal mucosa. Wait for a few minutes to ensure adequate anesthetic effect.
Estimate the length of tube which is to be inserted by measuring the distance from the tip of the nose, loop around the ear, and then down to roughly 5 cm below the xiphoid process. This point can be marked with a piece of tape on the tube. The end of the tube is lubricated with local anaesthetic.
[Commercially available tubes do come with marks but it is better to measure the length]
The patient is made to sit upright with the neck partially flexed. The tube is gently passed along the floor of the nose to the pharynx. The patient is asked to take deep breaths. The tube is pushed down the esophagus asking the patient to make swallowing movements during the push or he/she may be given sips of water to swallow to assist the passage. Once the tube is past the pharynx and enters the esophagus, it is easily inserted down into the stomach. Continue to advance the tube until the distance of the previously estimated length is reached. The tube must then be secured by taping it to nose and /or forehead to prevent it from moving.
The procedure should be stopped and the tube completely withdrawn, if at any time, the patient experiences respiratory distress, is unable to speak, has significant nasal hemorrhage, or if the tube meets significant resistance.
It is of utmost importance to ensure that the tube has not passed into the respiratory passages. If the tube enters the trachea, the patient may cough or a blow of air with each aspiration will be detected at the open end of the tube.
To check, the patient is asked to speak. If the patient is able to speak, then the tube has not passed through the vocal cords and/or lungs.
Confirmation of Placement of Nasogastric Tube
To confirm, some fluid from the tube is aspirated into a syringe. This fluid is then tested for the presence of gastric contents. It can be tested with pH paper. An acidic pH below or equal to 4 incidates gastric fluid. Biochemical determination of enzymes such as trypsin and pepsin or bilirubin etc may be carried out on the aspirated fluid to determine its gastric origin.
Alternatively, air can be injected through the tube. Detection of hissing sound by auscultation over the epigastrium indicates correct placement of the tube.
The most reliable way to ensure the correct placement of the nasogastric tube is by taking an X-ray of the chest and abdomen. This is mandatory if the NG tube is to be used for medication or food administration.
A tube position check is recommended before each feed and at least once per day.
If feeding through the NG tube is to continue for a longer period, then smaller diameter tubes should be used to avoid irritation and erosion of the nasal mucosa.
Complications of Nasogastric Tube Insertion
Mild patient discomfort is common. Generous lubrication, the use of local anesthetic, and a gentle technique all help in reducing patient’s discomfort. Throat irritation can be reduced by giving anesthetic lozenges (eg, benzocaine lozenges) prior to the procedure. Gagging or vomiting can occur during the procedure. Therefore, suction should always be ready to use in case of this event.
Minor complications include nose bleeding (epistaxis), rhinitis, sinusitis and pharyngitis.
Significant complications that may occur include esophageal perforation, damage to a surgical anastomosis or intracranial placement of the tube. If the tube enters the trachea or further into the respiratory passages and is not detected and feeding started, aspiration pneumonia and death may result.
Nasogastric intubation is contraindicated in the presence of severe facial trauma or facial bone fracture due to increased risk of airway obstruction as well as the possibility of inserting the tube intracranially. In such patients, an orogastric tube may be inserted.
Patients suffering from esophageal varices are at higher risk of bleeding as the veins in the lower esophagus are friable and prone to rupture during the procedure.