Nasogastric intubation is a medical process involving the insertion of a plastic tube (nasogastric tube or NG tube) through the nose, down the esophagus, and down into the stomach. Orogastric intubation is a similar process involving the insertion of a plastic tube (orogastric tube) through the mouth. Abraham Louis Levin invented the NG tube. Nasogastric tube is also known as Ryle's tube in Commonwealth countries, after John Alfred Ryle.

Uses

A nasogastric tube is used for feeding and administering drugs and other oral agents such as activated charcoal. For drugs and for minimal quantities of liquid, a syringe is used for injection into the tube. For continuous feeding, a gravity based system is employed, with the solution placed higher than the patient's stomach. If accrued supervision is required for the feeding, the tube is often connected to an electronic pump which can control and measure the patient's intake and signal any interruption in the feeding. Nasogastric tubes may also be used as an aid in the treatment of life-threatening eating disorders, especially if the patient is not compliant with eating. In such cases, a nasogastric tube may be inserted by force for feeding against the patient's will under restraint. Such a practice may be highly distressing for both patients and healthcare staff.

If the tube is to be used for continuous drainage, it is usually appended to a collector bag placed below the level of the patient's stomach; gravity empties the stomach's contents. It can also be appended to a suction system, however this method is often restricted to emergency situations, as the constant suction can easily damage the stomach's lining. In non-emergency situations, intermittent suction is often applied giving the benefits of suction without the untoward effects of damage to the stomach lining. This type of catheter tends to be more prone to suctioning against the stomach lining, which can cause damage and interfere with future function of the tube.

Materials

Nasogastric tubes are available in a variety of different materials, each with their own unique properties.

  • Polypropylene - This material is most common. It is less likely to kink, which can be beneficial for placement, but its rigidity makes it less suitable to be used for long term feeding.
  • Latex - These tubes tend to be thicker and can be difficult to place without proper lubrication. Latex tends to break down at faster rates compared to other materials. Allergies to latex are relatively common and latex tubes are more likely to be recognized as a foreign object by the body. The tube should be directed straight towards the back of the patient as it moves through the nasal cavity and down into the throat. When the tube enters the oropharynx and glides down the posterior pharyngeal wall, the patient may gag; in this situation the patient, if awake and alert, is asked to mimic swallowing or is given some water to sip through a straw, and the tube continues to be inserted as the patient swallows. Once the tube is past the pharynx and enters the esophagus, it is easily inserted down into the stomach. The tube must then be secured in place to prevent it from moving. There are several ways to secure an NG placement. One method and the least invasive is tape. Tape is positioned and wrapped around the NG tube onto the patients nose to prevent dislodgement. The other method is a device called the Applied Medical Technology, or AMT, bridle. This device uses a magnet inserted into both nares that connects at the nasal septum and then pulled through to one side and tied. This technology allows nurses to safely apply bridles. The use of bridle securement decreased the percentage of NGs lost from 53% to 9%. The use of a chest x-ray to confirm position is the expected standard in the UK, with Dr/ physician review and confirmation. Future techniques may include measuring the concentration of enzymes such as trypsin, pepsin, and bilirubin to confirm the correct placement of the NG tube. As enzyme testing becomes more practical, allowing measurements to be taken quickly and cheaply at the bedside, this technique may be used in combination with pH testing as an effective, less harmful replacement of X-ray confirmation. Ultrasonography alone is not sufficient to confirm position for gastric tube. If the tube is to remain in place then a tube position check is recommended before each feed and at least once per day.

Only smaller diameter (12 Fr or less in adults) nasogastric tubes are appropriate for long-term feeding, so as to avoid irritation and erosion of the nasal mucosa. These tubes often have guidewires to facilitate insertion. If feeding is required for a longer period of time, other options, such as placement of a PEG tube, should be considered.

Function of an NG tube properly placed and used for suction is maintained by flushing. This may be done by flushing small amounts of saline and air using a syringe or by flushing larger amounts of saline or water, and air, and then assessing for the air to circulate through one lumen of the tube, into the stomach, and out the other lumen. When these two techniques of flushing were compared, the latter was more effective.

Contraindications

The use of nasogastric intubation is contraindicated in patients with moderate-to-severe neck and facial fractures due to the increased risk of airway obstruction or improper tube placement. Special attention is necessary during insertion under these circumstances in order to avoid undue trauma to the esophagus. There is also a greater risk to patients with bleeding disorders, particularly those resulting from the distended sub-mucosal veins in the lower third of the esophagus known as esophageal varices which may be easily ruptured due to their friability and also in GERD (Gastro Esophageal Reflux Disease). Avanos Medical's Cortrak2 EAS recall, has been classified as a Class I recall by the FDA, following these reports.

See also

  • Force feeding
  • Feeding tube

References