Nasogastric intubation
Encyclopedia
Nasogastric intubation is a medical process involving the insertion of a plastic tube (nasogastric tube or NG tube) through the nose
, past the throat
, and down into the stomach
.
Nasogastric aspiration (suction) is the process of draining the stomach's contents via the tube. Nasogastric aspiration is mainly used to remove gastric secretions and swallowed air in patients with gastrointestinal obstructions. Nasogastric aspiration can also be used in poisoning situations when a potentially toxic liquid has been ingested, for preparation before surgery under anesthesia, and to extract samples of gastric liquid for analysis.
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-emergent situations, intermittent suction may be applied giving the benefits of suction without the untoward effects of damage to the stomach lining.
Suction drainage is used for patients who have undergone a pneumonectomy
in order to prevent anesthesia-related vomiting and possible aspiration of any stomach contents. Such aspiration would represent a serious risk of complications to patients recovering from this surgery.
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.
Great care must be taken to ensure that the tube has not passed through the larynx
into the trachea
and down into the bronchi. To ensure proper placement it is recommended (though not unequivocally confirmed) that injection of air into the tube be performed, if the air is heard in the stomach with a stethoscope, then the tube is in the correct position. Another more reliable method is to aspirate some fluid from the tube with a syringe
. This fluid is then tested with pH paper
(note not litmus paper
) to determine the acidity of the fluid. If the pH is 5.5 or below then the tube is in the correct position. If this is not possible then correct verification of tube position is obtained with an X-ray
of the chest/abdomen. This is the most reliable means of ensuring proper placement of an NG tube. 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. 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.
, esophageal varices, and/or obstructed airway.
The use of an NG tube is also contraindicated in patients who have had gastric bypass surgery.
Sometimes more significant complications occur including erosion of the nose where the tube is anchored, esophageal perforation, pulmonary aspiration, a collapsed lung, or intracranial placement of the tube.
Human nose
The visible part of the human nose is the protruding part of the face that bears the nostrils. The shape of the nose is determined by the ethmoid bone and the nasal septum, which consists mostly of cartilage and which separates the nostrils...
, past the throat
Throat
In vertebrate anatomy, the throat is the anterior part of the neck, in front of the vertebral column. It consists of the pharynx and larynx...
, and down into the stomach
Stomach
The stomach is a muscular, hollow, dilated part of the alimentary canal which functions as an important organ of the digestive tract in some animals, including vertebrates, echinoderms, insects , and molluscs. It is involved in the second phase of digestion, following mastication .The stomach is...
.
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 aspiration (suction) is the process of draining the stomach's contents via the tube. Nasogastric aspiration is mainly used to remove gastric secretions and swallowed air in patients with gastrointestinal obstructions. Nasogastric aspiration can also be used in poisoning situations when a potentially toxic liquid has been ingested, for preparation before surgery under anesthesia, and to extract samples of gastric liquid for analysis.
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-emergent situations, intermittent suction may be applied giving the benefits of suction without the untoward effects of damage to the stomach lining.
Suction drainage is used for patients who have undergone a pneumonectomy
Pneumonectomy
A pneumonectomy is a surgical procedure to remove a lung. Removal of just one lobe of the lung is specifically referred to as a lobectomy, and that of a segment of the lung as a wedge resection .-Indications:...
in order to prevent anesthesia-related vomiting and possible aspiration of any stomach contents. Such aspiration would represent a serious risk of complications to patients recovering from this surgery.
Technique
Before an NG tube is inserted the health care provider must measure with the tube from the tip of the patient's nose to their ear and down to the xyphoid process. Then the tube is marked at this level to ensure that the tube has been inserted far enough into the patient's stomach. Many commercially available stomach and duodenal tubes have several standard depth markings, for example 18" (46 cm), 22" (56 cm), 26" (66 cm) and 30" (76 cm) from distal end; infant feeding tubes often come with 1 cm depth markings. The end of a plastic tube is lubricated (local anesthetic, such as 2% xylocaine gel, may be used; in addition, nasal vasoconstrictor spray may be applied before the insertion) and inserted into one of the patient's anterior nares. The tube should be directed aiming down and back as it is moved through the nasal cavity and down into the throat. When the tube enters the oropharynxOropharynx
The Oropharynx reaches from the Uvula to the level of the hyoid bone.It opens anteriorly, through the isthmus faucium, into the mouth, while in its lateral wall, between the two palatine arches, is the palatine tonsil....
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
Pharynx
The human pharynx is the part of the throat situated immediately posterior to the mouth and nasal cavity, and anterior to the esophagus and larynx. The human pharynx is conventionally divided into three sections: the nasopharynx , the oropharynx , and the laryngopharynx...
and enters the esophagus
Esophagus
The esophagus is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. During swallowing, food passes from the mouth through the pharynx into the esophagus and travels via peristalsis to the stomach...
, it is easily inserted down into the stomach.
Great care must be taken to ensure that the tube has not passed through the larynx
Larynx
The larynx , commonly called the voice box, is an organ in the neck of amphibians, reptiles and mammals involved in breathing, sound production, and protecting the trachea against food aspiration. It manipulates pitch and volume...
into the trachea
Vertebrate trachea
In tetrapod anatomy the trachea, or windpipe, is a tube that connects the pharynx or larynx to the lungs, allowing the passage of air. It is lined with pseudostratified ciliated columnar epithelium cells with goblet cells that produce mucus...
and down into the bronchi. To ensure proper placement it is recommended (though not unequivocally confirmed) that injection of air into the tube be performed, if the air is heard in the stomach with a stethoscope, then the tube is in the correct position. Another more reliable method is to aspirate some fluid from the tube with a syringe
Syringe
A syringe is a simple pump consisting of a plunger that fits tightly in a tube. The plunger can be pulled and pushed along inside a cylindrical tube , allowing the syringe to take in and expel a liquid or gas through an orifice at the open end of the tube...
. This fluid is then tested with pH paper
PH indicator
A pH indicator is a halochromic chemical compound that is added in small amounts to a solution so that the pH of the solution can be determined visually. Hence a pH indicator is a chemical detector for hydronium ions or hydrogen ions in the Arrhenius model. Normally, the indicator causes the...
(note not litmus paper
Litmus test (chemistry)
Litmus is a water-soluble mixture of different dyes extracted from lichens, especially Roccella tinctoria. It is often absorbed onto filter paper to produce one of the oldest forms of pH indicator, used to test materials for acidity. Blue litmus paper turns red under acidic conditions and red...
) to determine the acidity of the fluid. If the pH is 5.5 or below then the tube is in the correct position. If this is not possible then correct verification of tube position is obtained with an X-ray
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
of the chest/abdomen. This is the most reliable means of ensuring proper placement of an NG tube. Future techniques may include measuring the concentration of enzymes such as trypsin
Trypsin
Trypsin is a serine protease found in the digestive system of many vertebrates, where it hydrolyses proteins. Trypsin is produced in the pancreas as the inactive proenzyme trypsinogen. Trypsin cleaves peptide chains mainly at the carboxyl side of the amino acids lysine or arginine, except when...
, pepsin
Pepsin
Pepsin is an enzyme whose precursor form is released by the chief cells in the stomach and that degrades food proteins into peptides. It was discovered in 1836 by Theodor Schwann who also coined its name from the Greek word pepsis, meaning digestion...
, and bilirubin
Bilirubin
Bilirubin is the yellow breakdown product of normal heme catabolism. Heme is found in hemoglobin, a principal component of red blood cells. Bilirubin is excreted in bile and urine, and elevated levels may indicate certain diseases...
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. 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
French catheter scale
The French scale or French gauge system is commonly used to measure the size of a catheter. It is most often abbreviated as Fr, but can often abbreviated as FR or F. It may also be abbreviated as CH or Ch in French speaking countries...
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.
Contraindications
The use of nasogastric intubation is contraindicated in patients with base of skull fractures, severe facial fractures especially to the nose and obstructed esophagusEsophagus
The esophagus is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. During swallowing, food passes from the mouth through the pharynx into the esophagus and travels via peristalsis to the stomach...
, esophageal varices, and/or obstructed airway.
The use of an NG tube is also contraindicated in patients who have had gastric bypass surgery.
Complications
Minor complications include nose bleeds, sinusitis, and a sore throat.Sometimes more significant complications occur including erosion of the nose where the tube is anchored, esophageal perforation, pulmonary aspiration, a collapsed lung, or intracranial placement of the tube.