Nose-gastric tube

Generality

The nasogastric tube is a long and flexible tube which, introduced into the stomach starting from the nose, can be used to:

• the administration of nutrients,
• the elimination of a certain undesired gastric content (gas, blood, accidentally ingested objects, etc.),
• gastric lavage,
• gastric decompression,
• drug administration
• lung expansion (is a favoring factor).
  

Made of polyurethane, PVC or silicone, modern nasogastric tubes are medical devices suitable for short / medium term use; their prolonged use, in fact, can cause unpleasant side effects.

There are two main types of nasogastric tube: the single lumen nasogastric tube, known as the Levin probe, and the double lumen nasogastric tube, known as the Salem probe. These two types of nasogastric tube differ in features such as maximum diameter or length, and clinical indications.

The introduction of the nasogastric tube in the stomach of an individual is a rather delicate procedure, which requires a certain skill and experience, on the part of the person who performs it.

What is the nasogastric tube?

The nasogastric tube is a long, flexible tube that, inserted into the nose and carried up to the stomach through the pharynx and esophagus, can serve various purposes, including mainly: the administration of nutrients and the elimination of a determined unwanted gastric content.

Also known as a naso-gastric probe, the nasogastric tube is actually a medical device.

Indications

Doctors use the nasogastric tube to:

• Provide artificial nutrition for people who are incapable or refuse to eat.

  Artificial nutrition made with a nasogastric tube is a form of enteral nutrition, called enteral nutrition through the nasogastric tube ;

• Empty the stomach of unwanted food, gas, blood or foreign objects accidentally ingested (clearly which can pass through the tube);
• Clean the stomach of highly dangerous toxic substances or an overdose of drugs / drugs. The stomach cleaning procedure, performed through a nasogastric tube, is called gastric lavage or gastric irrigation ;
• Provide for the so-called gastric decompression as a form of prevention of vomiting and treatment of gastric distension, in people with intestinal obstruction;
• Give drugs to people who are unconscious or have difficulty swallowing;
• Favor lung expansion in unconscious subjects and subjected to mechanical ventilation.

Normally, the nasogastric tube is a short / medium term solution, regardless of the indications, as its prolonged use can be very annoying and cause unpleasant side effects.

Therefore, taking enteral nutrition using the nasogastric tube as an example, the use of the latter is indicated:

• In the early stages of any incapacity or unwillingness to eat. After that, the transition to another form of artificial nutrition (enteral or parenteral) takes place;

or

• When a quick recovery of the ability to feed independently is expected. If these conditions are lacking, doctors immediately prefer to resort to artificial nutrition specifically designed for prolonged use.

DEEPENING ON ENTERAL NUTRITION

In medicine, any form of artificial nutrition takes the name of enteral, performed by means of a tube (or probe ) that opens into a section of the digestive system and, here, releases nutrients from an external resource.

There are at least 4 different types of enteral nutrition:

• The aforementioned enteral nutrition via the nasogastric tube;
• Enteral nutrition called PEG ( Percutaneous Endoscopic Gastrostomy ). This involves the insertion in the stomach of the probe for feeding, through a hole made on the abdomen and on the wall of the same stomach;
• The jejunostomy, which takes up the principles of PEG with the only difference that the insertion of the probe occurs in the jejunum, that is, a section of the small intestine;
• Enteral nutrition through a nose-jejunal tube, different from enteral feeding through a nasogastric tube due to the fact that the feeding probe opens into the section of the intestine called jejunum.

Features

There are two types of nasogastric tube: the nasogastric tube known as the " Levin probe " and the nasogastric tube known as the " Salem probe ".

PROBE OF LEVIN

The Levin probe is a single-lumen nasogastric tube, at most 125 centimeters long and with a diameter varying from 6 to 18 French (NB: a French or French unit is equivalent to 0.33 millimeters).

It can be used in enteral nutrition, in gastric decompression (in the presence of intestinal obstruction), in washing the stomach of dangerous toxic substances (gastric lavage) and in aspirating blood from the gastric compartment (ie from the stomach).

Levin small bore and large bore probes

There are Levin probes with a diameter between 6 and 12 French, specifically defined as " small bore " or "small lamp", and Levin probes with a diameter between 12 and 18 French, called " large bore " or "large lumen ".

Levin small bore probes are mainly used in enteral nutrition, while Levin large bore probes are particularly suitable for gastric decompression and aspiration of blood from the gastric compartment.

SALEM PROBE

The Salem probe is a double-lumen nasogastric tube, at most 120 centimeters long and with a diameter varying from 14 to 18 French .

It is indicated mainly for gastric decompression (in the presence of intestinal obstruction), although its use in gastric lavage procedures is not excluded.

REALIZATION MATERIALS

The most common materials for the realization of the current nasogastric tubes are: polyurethane, silicone and PVC ( polyvinyl chloride ).

Compared to PVC, polyurethane and silicone are much more resistant to the acidic environment of the stomach. Therefore, compared to PVC nasogastric probes, nasogastric probes made of polyurethane or silicone are more suitable for medium-duration use.

Application procedure

The application of a nasogastric tube is a non-trivial medical procedure, which requires some skill and some caution on the part of the person who performs it. For this reason, it is good that it is always personal to do it with appropriate preparation and good experience in the field in question.

The main steps in applying a nasogastric tube, which generally see a qualified nurse as the protagonist, are:

• If the patient is conscious, brief exposition of the procedure and agreement on a communicative signal that indicates some problems or the will to interrupt the installation of the nasogastric tube;
• Placement of the patient in a semi-sitting position, with the head supported by some cushions, neither too far back nor too far forward;
• Examination of the nostrils, in order to understand their exact anatomy and determine the best and most effective way to correctly insert the nasogastric tube;
• Measurement from the outside of the length that the nasogastric tube must possess. In general, nasogastric tubes are measured starting from the so-called nasal bridge (an anatomical part of the nose) up to the area located halfway between the sternum and the navel. It is clear that the length of the nasogastric tube is a variable parameter, different from patient to patient;
• Once the measurement has been made, marking with a felt-tip pen the nasogastric tube, so as to have a reference when inserting it;
• Lubrication of the nasogastric tube, to favor its future advancement within the digestive system;
• Introduction of the gastric tube-nose into the digestive tract. The introduction starts from the nose, continues to the pharynx and the esophagus and ends in the stomach. The previous length marking, which the nasogastric tube must possess, indicates when it is time to put an end to the introduction operation.

  The introduction is a delicate operation: those who perform it never work with force and are attentive to every gesture of the patient (eg: cough) as well as to any change in appearance (eg: sudden cyanosis);

• If the patient is conscious, call for swallowing, to facilitate the passage of the nasogastric tube;
• At the end of the introduction, check the position of the nasogastric tube, using specific tests;
• If the introduction has had full success, external fixing of the nasogastric tube, with adhesive tape.

WHAT ARE THE TESTS FOR CHECKING THE PROBE POSITION?

The tests useful to establish the correct positioning of the nasogastric tube are: the pH test on the aspirated liquid (if the tube has been inserted correctly, the aspirated liquid must have a pH equal to 4 or lower, except in exceptional cases) and the chest radiograph (shows whether the nasogastric tube flows into the stomach or not).

Risks and complications

The use of the nasogastric tube presents various risks and may give rise, in some circumstances, to serious complications.

A list of possible drawbacks related to the use of the nasogastric tube is as follows:

• If the patient is conscious, the procedure for inserting the tube, even if appropriate, can be painful;
• The inappropriate introduction of the nasogastric tube can cause damage to the anatomical portions crossed, therefore to the nose, pharynx, esophagus and / or stomach;
• If the introduction of the nasogastric tube is wrong and takes place in the trachea, instead of in the esophagus, there is a real risk of entering food and medicines in the lungs, rather than in the stomach (clearly this risk exists if the nasogastric tube it has a nutritional purpose or is used for the administration of drugs). This particular complication is called aspiration and can lead to lung infections (pneumonia);
• After the introduction of the nasogastric tube, disturbances may appear, such as: abdominal cramps, abdominal bloating, diarrhea, feeling of vomiting and / or nausea.

COMPLICATIONS RELATED TO PROLONGED USE

Prolonged use of the nasogastric tube has a high probability of causing ulcers and infections in the paranasal sinuses, throat, esophagus and / or stomach.

Contraindications

The use of the nasogastric tube has some contraindications, including:

• Recent history of a serious trauma to the middle portion of the face;
• Presence of fractures at the base of the skull;
• Recent history of nose surgery;
• Presence of esophageal varices. It is a potentially temporary contraindication;
• Presence of a stenosis of the esophagus. It is a potentially temporary contraindication;
• Presence of gastric stasis.

Results

If used in the right way, the nasogastric tube is a valid and very useful medical device. It is, in fact, effective both when it is used to administer food or medicines, and when it is used to cope with an intestinal obstruction or to cleanse the stomach of unwanted substances.

As stated, prolonged use of the nasogastric tube is harmful, and therefore not very effective, for therapeutic purposes.