|Year : 2010 | Volume
| Issue : 2 | Page : 37-44
Uses and hazards of nasogastric tube in gastrointestinal diseases: An update for clinicians
Department of Surgery, Ahmadu Bello University Teaching Hospital, Shika-Zaria, Nigeria
|Date of Web Publication||24-Mar-2011|
J G Makama
Department of Surgery, Ahmadu Bello University Teaching Hospital, Shika-Zaria
|How to cite this article:|
Makama J G. Uses and hazards of nasogastric tube in gastrointestinal diseases: An update for clinicians. Ann Nigerian Med 2010;4:37-44
|How to cite this URL:|
Makama J G. Uses and hazards of nasogastric tube in gastrointestinal diseases: An update for clinicians. Ann Nigerian Med [serial online] 2010 [cited 2014 Nov 23];4:37-44. Available from: http://www.anmjournal.com/text.asp?2010/4/2/37/78269
| Introduction|| |
Since its first description by Hunter,  the nasogastric (NG) tube has become a frequently used method of alleviating gastrointestinal symptoms. NG tubes are frequently used in the clinical setting for the management of patients who require decompression of the gastrointestinal tract, diagnosis and assessment, nutritional support and medication administration. , The insertion and management of NG tubes are procedures increasingly undertaken by nurses, interns, House officers, Medical Practitioners although, there is a wide variation in practice. ,, The use of NG tubes may be associated with complications.  Attention to tube size selection, assessment of tube position and the method of securing NG tubes are important components of care of NG tube to minimize the risks of NG tube-related complications and provide for optimal patient safety and comfort. Therefore the aim of this update is to highlight the uses, care and hazards of NG tube.
| The Mechanism of NG Tube|| |
The mechanism of NG tube could be looked at as a siphon and a conduit [Table 1].
If this fluid is allowed to accumulate, it may distend the stomach, increasing the risk of vomiting/reflux and aspiration, intra-abdominal pressure and subsequently splinting the diaphragm. The patient may develop respiratory embarrassment and reduced venous (IVC) return if intra-abdominal pressure continue to rise. 
| Efficiency of NG Tube|| |
The efficiency of a nasogastric (NG) tube could be conveniently deduced using this formula "phg" where
- p=Force/Area force/l x b
Thus, the wider the diameter of the tube, the shorter the length of the tube outside the patient's body, the more efficient is the NG tube for drainage. However, for feeding, the smaller the diameter, the better the function.
| Classification/Type|| |
NG tube can be classified base on various factors [Table 2].
Polyvinyl Chloride (PVC) - for short-term use up to 10 days (Ryles tubes - Pennine, Portex, Flocare). There is also a fine bore Medicina tube for short-term use (7-14 days) made of polyurethane. Polyurethane (PUR or fine bore) - for long-term use greater than 10 days (Corflo 6 -IOFr, Medicina 6-lOFr Flocare 6 - IOFr). In passive, which could be open or closed, the NG tube is left open or connected to a collecting system without the application of suction machine. 
In active, the NG tube is connected to a suction machine which could produce a slow but consistent evacuation of the gastric content. If for suction, intermittent connection to suction machine achieves better result than continuous type.  Set machine on type of suction and pressure, as it is prescribed. They are available in a range of sizes, pediatric and adult lengths.
| Indications|| |
The indications for passage of NG tube are summarized in the [Table 3].
| Contraindications|| |
Severe midface trauma: In severe midface trauma, the passage of a NG tube is absolutely contraindicated because there is high risk of malpositioning and false passage
Recent nasal surgery: In recent nasal surgery the risk of disruption and false passage is also high.
Esophageal varices or stricture
Recent banding or cautery of esophageal varices
Fractured base of skull
| NG Tube Selection|| |
Tubes of various sizes have been used [5,6] and selection of an appropriate size is largely dependent on the intended use for the tube and the anticipated duration it will be in situ.
Soft, flexible, small-diameter (8-14 Fr) tubes are frequently used for patients who require enteral feeding for less than 6 weeks. However firmer, less flexible, large-diameter tubes (16 Fr or larger) are used to administer medications, gastric decompression, and for short-term feeding (usually shorter than 1 week).
Reported advantages of small-bore NG tubes compared to large-bore tubes include less trauma to the nasal mucosa both during insertion and while in situ and better patient tolerance.
| Procedure of Passage of NG Tube|| |
The entire procedure is done under aseptic condition. Gather all necessary equipment as discussed in [Table 4]. Explain the procedure to the patient and show equipment if possible. Obtain consent/counseling.
| Positioning of Patient|| |
If possible, sit patient upright for optimal neck/stomach alignment. If not, sit patient in semiupright position.
Examine nostrils for deformity/obstructions to determine best side for insertion. Measure tubing from bridge of nose to earlobe then to xiphoid sternum and mark with tape. Alternatively, mark measured length with a marker or note the distance .
| Anesthesia|| |
Lignocaine gel (2%)
Nebulized lignocaine (1 - 4%) via face mask
Anesthetic spray (benzocaine/cetacaine)
Lubricate 2-4 inches with xylocaine gel or anesthetic spray. Lubricate 2-4 inches of tube with lubricant (preferably 2% Xylocaine). This procedure is very uncomfortable for many patients, so a squirt of Xylocaine jelly in the nostril, and a spray of Xylocaine to the back of the throat will help alleviate the discomfort.
Pass tube via either nare posteriorly, past the pharynx into the esophagus and then the stomach.
Instruct the patient to swallow (you may offer ice chips/water) and advance the tube as the patient swallows. Swallowing of small sips of water may enhance passage of tube into esophagus.
Should the tube meet resistance/obstruction and cannot be advanced, it is advisable practitioners should not make more than three attempts to insert or should stop immediately if there is distress or risk of physical harm to the patient. If the patient shows any evidence of respiratory distress the tube should be withdrawn immediately. If the respiratory distress is prolonged or worsens medical advice should be sought. If the tube insertion is unsuccessful, inform a more experienced professional and reassure the patient. If resistance is met, rotate tube slowly with downward advancement toward the ear. Do not force. Withdraw tube immediately if changes occur in patient's respiratory status, if tube coils in mouth, if the patient begins to cough or turns pretty colors. Advance tube until mark is reached if you are in the right path.
| Verification of Placement|| |
Check for placement ,, by attaching syringe to free end of the tube, aspirate sample of gastric contents. The other best practice is to test the pH of the aspirated contents to ensure that the contents are acidic using litmus strip. The pH should be below 6. Obtain an X-ray to verify placement before instilling any feeding/medication , or if you have concerns about the placement of the tube. Alternatively, listen to stomach while passing air into tube with 20 ml syringe, ask patient to talk (choking indicates it is in the bronchi),  place tube under water, bubbles indicate it is in bronchi. Consensus holds that more than one technique should be used and an X-ray should be obtained if any doubt exists about placement.
| Passage of NG Tube in Special Situations|| |
It is important to know that extra care is required in very special situations such as deeply unconscious patients and children who may not be able to complain to the physician.
| Maintenance of NG Tube|| |
Place securely, using adhesives, around nose and use pin to pin it to patient's gown. Flush regularly to avoid occlusion.
Check length of tube regularly by checking line or tape position, checking nasal fixation.
Observe for signs of respiratory discomfort.
Suction with low pressure suction machine occasionally [Figure 1],[Figure 2],[Figure 3],[Figure 4],[Figure 5],[Figure 6],[[Figure 7],[Figure 8],[Figure 9],[Figure10].
Securing a NG tube
It is absolutely important to ensure the NG tube is secured and the system is intact to prevent dislodgement and infection or irritation of the nostril. NG tube has been secured using various techniques and materials. The commonly used techniques includes adhesive, clips, safety pins and suture to secure the NG tube. 
Regular monitoring of the NG tube is very necessary. A proper chart of daily output from the tube in terms of volume, color, viscosity and content is absolutely necessary.  Effort must be put in place to replenish the volume of fluid lost from the NG tube through intravenous fluid therapy. The length of the tube and point(s) of securing the tube must be to examine regularly for evidence of dislodgement, kinking, patient lying on top of the tube or knotting. Documentation, such as the reason for the tube insertion, type and size of tube, the nature and amount of aspirate, the type of suction and pressure setting if for suction, the nature and amount of drainage and the effectiveness of the intervention are absolutely important in the care of an NG tube. ,,
Generally, NG tube should be removed once the drainage is minimal, its output has become <25-50m1/day, or the NG tube has stopped serving the desired function. , The character and viscosity of the drainage fluid are occasionally considered before drains are removed such as an initial hemorrhagic effluent becoming clear fluid.  Bowel sounds should be present and normal, no abdominal distension, patient should be able to move his bowel and passes flatus. 
| Advantages|| |
Affordability: In gastrointestinal diseases, NG tube has been quite useful and its affordability is one of the factors that have encouraged most practitioners to continue to use it.
Availability: It is readily available in most cases. Requires minimal anesthesia during its insertion.
Easy to pass: Once it has passed the oropharynx, the ease of passage is augmented by patient's act of swallowing.
| Disadvantages|| |
Discomfort: This is one of the major factors for NG tube rejection among patients. However, it is advisable to appropriately select the size of the tube. NG tube should be properly secured and then removed as soon as it has served its purpose.
Psychologic trauma: To some patient, it is really a psychological trauma to have an NG tube in situ.
Complications: The fact that the use of NG tube is not without complications or consequences should make a medical practitioner to be cautious in its application.
Restriction to movement: When a patient is on NG tube, his movement is quite restricted as the tube may be secured to his beddings.
| NG Tube Syndrome|| |
NG tube syndrome (NTS) is an uncommon complication of an indwelling NG tube.  Ulceration and infection in the posterior cricoid region causes dysfunction in the abduction of the vocal cords and may seriously compromise patients' airway. This pathology should be considered in patients with prolonged NG intubation who start with moderate pharyngeal pain
| Hazards of NG Tube|| |
Pharyngeal discomfort: Nasopharyngeal discomfort is one of the major factors of NG tube rejection among patients.  It is, therefore, necessary to explain the procedure, the likely discomfort and the rationale of the procedure to the patient. Usually, patient is reassured following this counseling.
Erosion of nares: Erosion of the nares has been noted to be a serious hazard of NG tube insertion particularly when it is not properly lubricated. 
Sinusitis: Cases of sinusitis have been reported following passage of an NG tube. This may happen when the procedure is not aseptic. ,
Nasotracheal intubation: Malpositioning of the NG tube into the trachea is a common complication of NG tube passage even among experienced medical practitioners. , Therefore, it is necessary to verify its position before any medication or fluid is administered into the tube.
Gastritis: Gastritis is a frequent complication of NG tube insertion.  In this case, continue pressure and irritation of the stomach by the tip of the NG tube have been implicated. Frequent changing and alteration of the NG tube and the set up should be reduced so as to minimize incidence of gastritis in patients with NG tube in situ.
Epistaxis: Epistaxis resulting from minor bruises during insertion is a common complication particularly in hypertensive and in patients with coagulopathy.  Therefore, it is necessary to be gently and be more cautious in patients suspected to hypertensive or have abnormal coagulation.
| Tube Enteral Complications|| |
Tube knotting and impaction in the posterior nasopharynx:  The NG tube could occasionally coiled and get knotted within the esophagus. It may also accumulate in the posterior nasopharynx thereby causing obstruction to both airway and the esophagus.
Tube beyond the pylorus: The tube could be pushed beyond the pylorus in which case it becomes counter-productive particularly if it was meant for gastric drainage. 
Tube double backing and kinking: When this happens, the tube becomes block and stop functioning.
Tube rupture: There are reported  cases of tube rupturing particularly during feeding when the pressure of the feeding syringe is high or is forcefully pushed.
Tube breakage: This may happen when an expired tube is wrongly inserted into a patient.
Following repair of choanal atresia and transnasal transphenoidal surgery Following maxillofacial trauma. 
Bronchial placement: Bronchial placement may cause airway obstruction which may lead to atelectasis, pneumonia and lung abscess. 
Bronchial perforation is often a deadly complication in this patients. 
Pleural cavity penetration-Its quite rare but very serious complication of NG tube insertion.  It may cause severe pneumothorax.
Isocalothorax (enteral feed hydrothorax) particularly when it was meant for feeding and the feeding was commenced without prior verification of its placement.
Empyema and sepsis is also a known fatal complication of passage of NG tube.  Pulmonary hemorrhage particularly when a major vessel is injured. 
Erosion into retroesophageal aberrant right subclavian artery have been reported in the past. ,,
Nasogastric tube syndrome (NTS) is a rarely reported complication of NGT use that can cause life-threatening laryngeal obstruction. The syndrome results from post-cricoid ulceration, which affects the posterior cricoarytenoid muscles, thus causing vocal cord abduction paralysis and upper airway obstruction. 
| Recent Advances|| |
The use of flexible fiberoptic nasoendoscope to insert the NG tube under direct vision is quite handy where traditional methods have failed. 
NGT stabilizers-invented to reduce the complications due to tube movement and also the reaction force produced by the indwelling portion of the tube is also a major advancement.
Developments in tube material with polyurethane ensure greater tolerance, patient comfort and tube longevity.
| Conclusions|| |
The knowledge of the use of NGTs is integral in the medical practice as a whole, more so in gastrointestinal diseases because of its wide range of uses.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure10]
[Table 1], [Table 2], [Table 3], [Table 4]