The following guide on Nasogastric Tube insertion relates to adult, conscious, co-operative patients that require no spinal precautions.
The first thing to say about insertion of a nasogastric (NG) tube is that it is probably going to be one of the more noxious things that you will do to your patient. Thorough preparation, and explanation before proceeding with reassurance, and confidence are essential for a successful first pass.
Indications for NG tube insertion include:
- Aspiration of gastric contents / emptying of the stomach.
- Gastric decompression.
- Administration of feeding or medication.
- Administration of radiographic contrast to the GI tract.
Equipment: Assemble the following:
- Personal protective equipment.
Gown, gloves, eye/face protection.
- NG tube.
- Bladder (60ml) syringe.
- pH indicator strips.
- Lubricant: Sterile water, KY jelly, Catheter jelly.
- Cup of water and straw or chipped ice.
- Vomit bag or bowl (just in case). Towel to cover front of patient during procedure.
- Adhesive securing tape.
- Drainage bag (if required) or spigot.
- Wash your hands and don gown and eye protection (preferably a face shield).
If you are inserting the tube in a patient with influenza also wear a P95 mask.
- Measure the correct tube length. From the tip of the patients nose to the tragus of the ear and then down to the xiphisternum. The NG tube is marked off in centimeter increments so you can just note the length. I like to wrap a small length of tape around the tube at the mark as an extra prompt.
- Lubricate the tip and the first few centimeters of the tube. Often sterile water is all you will need.
(Note: if you are using KY jelly. This is alkaline and has the potential to alter your pH testing if you use a lot of it).
- Position the patient. Ideal position is sitting upright with the head flexed forward (chin on chest). This tends to allow the tube to advance against the posterior pharyngeal wall facilitating a smooth passage into the oesophagus.
- Tell the patient that you are going to gently support them, and place your non dominant hand against the back of their head. Advance the tube into the nostril of choice.
The mistake made here is to advance the tube upwards (the way your finger goes when you pick your nose). The tube should be advanced at 90 degrees to the face.
If there is resistance gently rotate the tube and retry
- As the tube passes into the nasopharynx, ask the patient to sip a mouthful of water. This is to close the glottis facilitating passage of the tube into the oesophagus rather than the trachea.
- Smoothly advance the tube until your marker reaches the nostril.
- Secure with tape.
- The gold standard confirmation that the tube is in the stomach is an Xray.
- Using a bladder syringe gently withdraw an aspirate sample. Test the pH of this sample. A pH of less than 5.5 confirms that the tube is in the stomach.
If aspirate pH is greater than 5.5 or the patient is showing signs of respiratory distress remove the tube and begin again.
Note:There are some limitations to the testing for gastric pH. Stomach pH can be affected by medications particularly proton pump inhibitors (e.g. Omeprazole, Lansoprazole, Pantoprazole) and H2 receptor antagonists (e.g. Cimetidine, Ranitidine, Nizatidine) or by dilution of gastric acid by feed.
If you are unable to obtain aspirate and you think you might actually be in the stomach, secure the tape and re-aspirate in 10 minutes.
If after 10 minutes you are still unable to obtain an aspirate, consideration to confirm placement with a chest XR should be made.
Note: Using the bladder syringe to inject air down the tube whilst auscultating over the stomach is unreliable and should not be used as a definitive confirmation.
The NG tube must not be used to instil medication or fluid until absolute confirmation is obtained.
Check tube security. Take time to well secure your tube. There are plenty of tapes designed specifically for securing them.
- Any suspected skull fractures (orogastric route must be used).
- Maxillofacial injuries or disorders.
- Recent oropharangeal surgery.
Once the procedure is complete, documentation should be made in the patient notes including:
- Size of the tube
- Length of the tube at the nose.
- pH of aspirate obtained to confirm placement.
- Any problems or issues during insertion.
Tips & Tricks.
Xylocaine Gel: One trick I employ is to use some Xylocaine Gel (used for urinary catheter insertion). I use the applicator to apply a small gob just inside the patients nostril. I then ask them to sniff it up as if they have a runny nose. I also apply a second gob on the back of their tongue and ask them to swallow it. In my experience this often provides some degree of anaesthesia making it a less unpleasant experience.
Use a cold tube: One of the main problems with NG insertion arises because of a weak point in its construction. The array of holes at the distal 6 cm of the tube make this area all flaccidimo. As the tube advances it tends to snag up against the pyriform sinuses or arytenoid
cartilage curling over and coiling above the oesophagus.
So if you anticipate a tricky NG insertion, one tip is to keep some tubes stored in their packaging in the fridge.
This adds some rigidity to the whole thing. Also, the tube retains its curl memory which can be used to advantage.
The tube is fed into the nostril with the concave shape pressing downwards against the floor of the nasal passage:
Upon reaching the oropharynx, the nasogastric tube is rotated through 180 degrees bringing its tip up against the posterior pharyngeal wall. This then allows the tip to be kept closely applied to the posterior pharyngeal wall, encouraging it to enter the oesophagus. It is important at this point to lift the chin and observe the neck whilst slowly feeding the nasogastric tube into the nose. Any bulging noticed at the neck can be corrected by slight rotation of the nasogastric tube.
Reference: Anaesthesia Feb 2004
Be careful with using stiff NG tubes as injuries to vascular soft tissues are more likely.
Chipped Ice: Sometimes instead of asking the patient to swallow water, I place a teaspoon full of chipped ice in their mouth just before I begin to advance the tube, and then ask them to swallow it as I traverse the glottis.
I find the cold ice provides a distractive stimulus as the tube is passed. The small amount of ice melts quickly and I have not experienced any problems as far as aspiration risk etc.