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Involves the insertion of a plastic nasogastric tube or NG tube, through the nose, past the throat, and down into the stomach.
When continuous feeding is required a gravity based system is employed, with the solution placed higher than the patient’s stomach.
Nasogastric tubes may also be used for life threatening eating disorders.
Nasogastric tubes may be used to drain the stomach’s contents.
Nasogastric suction is the process of draining the stomach’s contents via the tube, and is mainly used to remove gastrointestinal secretions and swallowed air in patients with gastrointestinal obstructions.
Occasionally nasogastric aspiration can also be used to remove potentially toxic liquid or drugs that have been ingested.
Nasogastric intubation may be used for preparation before surgery under anaesthesia, and to extract samples of gastric liquid for analysis.
The tube can be used for continuous drainage, and connected to a bag placed below the level of the stomach.
Continuous drainage may use gravity to empty the stomach’s contents, or be connected to a suction system.
Types of nasogastric tubes include:
Levin catheter, which is a single lumen, small bore NG tube, used for administration of medication or nutrition.
Salem Sump catheter, which is a large bore NG tube with double lumen: allows for aspiration in one lumen, and venting in the other to reduce negative pressure and prevent gastric mucosa from being drawn into the catheter.
Dobhoff tube, which is a small bore NG tube with a weight at the end intended to pull it by gravity during insertion.
Prior to NG tube insertion, it is measured from the tip of the patient’s nose, loop around their ear and then down to roughly 5 cm below the xiphoid process.
The tube is marked at this level to ensure that the tube has been inserted far enough into the patient’s stomach.
Many stomach and duodenal tubes have several standard depth markings for use.
The end of a plastic tube is lubricated with local anesthetic, such as 2% xylocaine gel, and a nasal vasoconstrictor and/or anesthetic spray may be applied before the insertion and inserted into one of the patient’s anterior nares.
The tube is directed straight towards the back of the patient as it moves through the nasal cavity and down into the throat.
In the oropharynx it glides down the posterior pharyngeal wall, often prompting
patient to gag,
Such gagging can be relieved by the patient mimicking swallowing or sipping water through a straw
The tube is past beyond the pharynx and enters the esophagus, and then into the stomach.
Once the tube reaches the stomach the tube must then be secured.
Care is taken to ensure that the tube has not passed through the larynx into the trachea and down into the bronchi, and correct verification of tube position can be obtained with an X-ray of the chest/abdomen.
Placement of the tube position is checked before each feed and at least once per day.
Small diameter (12 Fr or less) nasogastric tubes are appropriate for long-term feeding, to avoid irritation and erosion of the nasal mucosa.
NG tube placement is maintained by flushing with saline or air using a syringe.
The use of nasogastric intubation is contraindicated with neck and facial fractures due to the increased risk of airway obstruction or improper tube placement.
Caution is required to prevent bleeding from esophageal veins or friable mucosa in GERR.
Complications of nasogastric intubation include nose bleeds, sinusitis, sore throat, erosion of the nose where the tube is anchored, esophageal perforation, damage to a surgical anastomosis, pulmonary aspiration, collapsed lung, or intracranial placement of the tube.
An independent risk factor for development of postoperative pneumonia.
Increased risk of gastroesophageal reflux.