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Nasogastric Tubes

Nasogastric tubes (NGTs) are frequently placed in surgical patients to decompress the stomach and minimize nausea/ vomiting while allowing bowel rest. For intubated ICU patients, this is frequently an orogastric tube, passed from the mouth to the stomach.


The anatomy of an NGT

  • Lumen: this is the inner cylindrical hollow conduit that allows gastric contents to be suctioned out and potentially allows medication and nutrition to be given (depending on the clinical situation).

  • Multiple holes to allow gastric contents to be suctioned into the lumen of the tube

  • Side port: if nasogastric tubes were like straws, with only one lumen, they would adhere tightly to the stomach wall when suction was applied. Thankfully, NG tubes have a side port (the blue ventilation port) that allows air to flow into the stomach, preventing the tube from giving the stomach a suction hickey.

  • Markings on the tube indicate how far the tube has been inserted.

  • A white line along the length of the tube (radiopaque). When viewed on an x-ray, the tube position can be confirmed by noting the location of the break in the radio-opaque line, which corresponds with the most proximal hole in the tube.


Basic Equipment

There is some basic equipment that you need to have at the bedside before inserting an NGT

  • The NG tube and a packet of lubricant

  • A large basin (in case the patient vomits)

  • Suction tubing to connect to a canister with working suction

  • Cup of water with straw (if not contraindicated)



Placement


Preparation

  1. Picking your tube size. Tubes range from 8-18 French. For adults, use 16 or 18. Avoid using a pediatric tube or anything smaller than a 16 Fr. Small tubes will just end up clogged. You can consider having one size smaller just in case you meet a lot of resistance and want to attempt a smaller caliber.

  2. Running the tube underwater. Some suggest that warm water helps by making the tube more pliable, others say cold water helps by making the tube softer. I haven't found one to be more helpful than the other. Try and see what works for you.

  3. Explain the procedure to the patient. Advise them that they might gag and vomit, and that’s ok. It’s not unexpected when you have a plastic tube through your nose and esophagus. Have the basin ready.

  4. Tell the patient their job is to swallow and keep swallowing. Tell them they might feel an urge to cough or gag, but they should try to resist that and focus on swallowing.

  5. If not contraindicated (ie aspiration risk, etc), have the patient hold a cup of water (with straw) in the hand opposite from where you're standing. Note- bowel obstruction is not a contraindication- once you place the tube, you will evacuate whatever the patient swallowed.


Positioning and insertion

  1. Raise the head of the bed and have the patient upright as much as possible and have them put their chin to their chest.

  2. Lubricate the end of the tube. Place the tip of the tube just inside the nares and then advance parallel to the floor…not up.

  3. You can place your hand on the back of the patient's head to gently keep their head from flying back, which is the natural reaction to a huge piece of plastic in your nose.

  4. Keep advancing the tube while encouraging the patient to swallow.

  5. The gastroesophageal (GE) junction is usually about 40 cm from the beginning of the esophagus. The tube must get past the GE junction to effectively decompress the stomach.


Post-placement

  1. Connect your tube to suction. There is a small plastic connector with tapered ends- one end connects to the suction tubing and the other end connects to the clear port. You can place to low intermittent or continuous suction- this is usually provider or institution dependent. You do NOT need a chest x-ray to confirm that an NGT is in the stomach before you place it to suction- if gastric contents are being suctioned, this confirms the position.

  2. You DO need a radiograph before instilling medication or enteral feeds.


Risks of nasogastric tubes

  1. Non-functional tube- an NGT is nothing more than a straw or a garden hose- except for one thing. If you were to place a garden hose into someone's stomach and apply suction, it would just adhere to the stomach wall. This can lead to suction hickeys, which are precursors to ulcers/ bleeding. But most importantly, this will cause the tube to be ineffective. The solution is the blue ventilation port- it allows air to pass into the stomach and keeps the tube from being suctioned against the stomach wall. [this was explained above in the anatomy section- but it's so important that it deserves repetition]

  2. Naso-pulmonary tube- accidental insertion into the lung. For an awake interactive patient, this will be evident by your patient's reaction- if they have a tube in their lung, they will cough. This can even cause a pneumothorax (personally never seen it, but it's been described). In an intubated patient, it might not be noticed until x-ray for checking placement.

  3. Tube curled and tip directed upward in the esophagus. Two risks- ineffective gastric decompression and misdirected meds and feeds (back up in esophagus instead of into stomach).

  4. Aspiration- an NGT essentially stents the lower esophageal sphincter open. So if your patient is lying flat (ie asleep), you MUST ensure that the NGT is functional. Especially in the case of a bowel obstruction (patient can vomit and aspirate) or if your patient has decreased mobility and isn’t able to reposition themselves quickly to avoid aspirating.

  5. Clogged tube- risk of aspiration, inability to give meds/ enteral nutrition.


The anti-reflux valve

You might notice another piece of plastic in the NGT packaging. I didn't mention the anti-reflux valve, that short blue and white plastic piece that suspiciously seems to fit perfectly into the blue ventilation port. According to the manufacturer (CR Bard), this piece of plastic is supposed to be inserted at the end of the blue port and allow air entrainment to prevent the suction hickey on the stomach. It also prevents gastric contents that reflux into the port from spilling onto the sheets. HOWEVER-- the caveat is that when gastric contents are refluxing into the blue ventilation port, it's supposed to be take as an indicator that the valve must be removed and air must be flushed into the blue ventilation port. This is the reason the anti-reflux valves are despised by most surgeons- once the blue ventilation port is coated with gastric contents, if they're not flushed, the NGT is essentially converted to a straw. Yes, the port may spit up some gastric contents.

However, the solution is NOT to replace the anti-reflux valve into the blue side port. Instead, the solution is to flush air into the blue port to clear it out. This is the primary task of maintaining a functional tube. You should hear faint sounds of air movement when you listen to the blue port- this means it’s working! [see video] The problem, and the reason we routinely throw these away, is the fact that they aren’t routinely removed and flushed, so they get clogged. When the blue port is clogged, the tube becomes non-functional, which can lead to gastric distension, nausea/ vomiting, and aspiration. “Minimal output” is not always reassuring with an NGT- it might be because the patient is improving, but it’s just as likely that the tube isn’t working because it isn't being maintained correctly.

It's not an exaggeration to say this is a life or death issue. An elderly patient with a bowel obstruction and a non-functional tube→ gastric distention + widely patent gastroesophageal junction + laying flat at night→ aspiration, pneumonia, death. Functional tubes are also crucial for patients with foregut procedures. For example, a repair of a stomach or proximal small bowel injury can be protected by a functional nasogastric tube- this minimizes air/ fluid passing by and exerting pressure on the repair. Please note- the blue ventilation port MAY reflux and spill out gastric contents. Two solutions are to place a chux under the end or to place the syringe of a Toomey at the end (see video). Just remember- if this happens, do NOT solve the problem by inserting the anti-reflux valve. Instead, use a Toomey syringe to flush air into the blue ventilation port.


CAUTION! There are caveats to this- specifically patients with foregut surgery (anywhere from the mouth through the first part of the small intestine). Patients with these clinical scenarios should have explicit instructions to the nursing staff on how the tubes are to be maintained.


But it makes too much noise?!

A patient who can complain about a whistling NGT is a patient who is much less likely like to aspirate and need to be intubated than a patient who doesn't have a whistling NGT.

But it makes a mess?!

See solutions above- chux pad or place a Toomey syringe.


How to maintain a functional NGT 


How to use the anti-reflux valve



So those are the basics. If I didn’t teach you any handy tricks, hold on for one last disclosure… the final secret to my success. I've used this trick many times for patients who are overly anxious or distressed at the process of having an NGT placed. For example, the patient who has had traumatic NGT placements previously (patients have shared so many horror stories with me) or is on edge in general. Two years ago, I was managing a burn patient in the ED. While the ED physician was prepping for a nasal laryngoscopy, he showed me a trick that I still use to this day. Using CTAs (cotton tip applicators, or Q-tips if you insist on a brand name), he anesthetized the patient's nasal passage with viscous lidocaine. He covered the cotton tip of 1-2 CTAs with the clear hair-gel consistency goop (the lidocaine), and then slowly advanced this along the nasal passage. Initially, they sat right inside the opening of the nares, resting for maybe 30-45 seconds. Then the lidocaine was reapplied, and the CTAs were advanced slightly to repeat the process. This continued through the entire length of the nasal passage. In addition to the nasal anesthetic, the patient was given a medicine cup with more viscous lidocaine to swallow. *Note- warn the patient that they MIGHT get the sensation that they can't breathe. They will still be able to breathe fine, but when the upper airway is anesthetized, it alters the sensation of airflow.

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