How to Aspirate a Nasogastric (NG) Tube

Aspirating an NG tube means drawing a little fluid back up the tube with a syringe so you can check that its tip is sitting in the stomach before anything goes down it. A tube can slip into the food pipe or the lungs without any obvious sign, and putting feed into the lungs can be deadly.1HSSIB. Investigation report: Placement of nasogastric tubes The check rests on one fact: stomach fluid is strongly acidic, and fluid from the lungs is not.

Step-by-Step How to Aspirate an NG Tube

Start with preparation:

  • Wash your hands and put on clean gloves before you handle the tube.2Medbridge. Nasogastric Tube Insertion Procedure
  • Gather a 60ml enteral syringe, pH test strips, and a record sheet. The pH is simply a number showing how acidic a liquid is.
  • Check that the marking on the tube where it leaves the nose hasn’t changed since the last check.

Then draw back and test:

  • Close or clamp the tube, attach the syringe, open the tube, and pull the plunger back slowly.
  • You only need a few drops of the fluid you draw back, about 0.5 to 1ml.
  • Drop the fluid onto the pH strip and compare the colour with the chart after the time stated on the pack.
  • Write down the reading, the date and time, and the tube marking.

Pull gently. Pulling hard can suck the stomach lining against the holes at the tip of the tube and block the flow. If the plunger springs back, pause before trying again rather than pulling harder.

A 60ml syringe is used because smaller syringes create much higher pressure when pushed, which is a risk to the tube and stomach. An enteral syringe is also designed to fit the tube port and not an intravenous line, which helps prevent feed or medicine going into a vein by mistake.

The first drops may not be fresh stomach fluid. Liquid can sit in the tube from the last flush, so the first millilitre may be water or old feed. Follow your team’s advice on whether to discard it and draw again. Discard the aspirate, or return it only as your team has told you, and never reuse it for the pH test of a later check.

Use paper made for this job, marked in half-point steps, and read it in good light, because colours close to 5.5 look very similar. If you can’t decide between two colours, treat the reading as the higher one.

Do the check before every feed or dose of medicine, after vomiting, a coughing fit, or retching, and whenever the tube looks as if it has moved. Use a clean syringe, close the tube port afterwards, and throw away gloves and used strips as instructed.

What pH Reading Means It Is Safe to Feed

Stomach fluid usually reads between 1 and 5.3The Royal Children’s Hospital Melbourne. Nasogastric and Orogastric Tube Insertion and Management That is why UK hospital and home guidance treats 5.5 or below as confirming the tube is in the stomach. Fluid from the airways has been found no lower than 6.4PubMed. Determination of a practical pH cutoff level for reliable confirmation of nasogastric tube placement One misplaced tube once gave a reading of 5.5, so some hospitals use 5 as their cutoff instead.5PubMed. Determination of a practical pH cutoff level for reliable confirmation of nasogastric tube placement If your team gave you 5, follow that.

The test is good but not perfect. A cutoff of 5.5 correctly picks out about 9 in 10 tubes that are in the stomach and rules out a similar share that are not.6Elsevier / International Journal of Nursing Studies. Accuracy of biochemical markers for predicting nasogastric tube placement in adults–a systematic review of diagnostic studies Many readings above 5.5 come from tubes that are actually in the right place, so a high reading means checking again.7Elsevier / International Journal of Nursing Studies. Accuracy of biochemical markers for predicting nasogastric tube placement in adults–a systematic review of diagnostic studies

In practice, you match the strip’s colour to the printed chart. A reading of 5 or 5.5 is acceptable under the usual cutoff, while anything above 5.5 is not.

A few common mistakes are worth avoiding. Don’t round a reading between 5.5 and 6 down to 5.5, and don’t repeat the test on the same strip.

Above 5.5, pause the feed. You may be able to try again after a wait; write down each attempt with the time. If a second or third try still reads high, contact your nurse or team rather than continuing to test.

What to Do If You Can’t Get Any Aspirate

Stay put for the full time, since moving around lets fluid shift away from the tip, and retest after about 20 minutes rather than every couple of minutes. To push air in, use a clean 60ml syringe, push gently, and draw back straight away. Air does not show where the tube is, so never use it as a position check on its own.

Water flushes don’t help. Water dilutes the fluid in the stomach and pushes the reading up, and it can go somewhere harmful if the tube is in the wrong place.

If you still get nothing after these steps, don’t feed, and contact your nurse or team. Repeated attempts to move or reposition a tube carry their own risk of it going into the airway.16PubMed. Pulmonary complications of 9931 narrow-bore nasoenteric tubes during blind placement: a critical review When you call, have ready the times of each attempt and any readings, whether the tube marking has moved, and any coughing or breathing changes.

Why Listening for Air or Looking at the Fluid Isn’t Enough

The whoosh test means pushing air down the tube while listening over the stomach with a stethoscope for a bubbling sound. It was widely taught in the past, so older guides, or people who learned it that way, may still recommend it. Current guidance does not accept it as a way to confirm position.

Listening with a stethoscope while pushing air down the tube cannot reliably tell when the tube is outside the stomach.17PubMed Central. Nasogastric tube insertion length measurement and tip verification in adults: a narrative review In reviewed case reports of children, this method missed every misplaced tube it was used on, and four of those children died.18PubMed Central. Nasogastric tube insertion length measurement and tip verification in adults: a narrative review Air pushed into the lung or food pipe can still produce a sound that seems like stomach air, and even trained staff cannot tell the difference by ear.

Fluid colour is no better on its own. Stomach fluid is usually cloudy and green, tan, off-white, or brown.19PubMed. Visual characteristics of aspirates from feeding tubes as a method for predicting tube location Airway mucus can look tan or off-white too, so colour can’t rule out the lungs.20PubMed. Visual characteristics of aspirates from feeding tubes as a method for predicting tube location Colour can still offer a hint, though not a reliable one: clear yellow fluid may suggest the tip has gone further into the gut. Mention any unusual colour to your nurse.

How Medicines and Feeds Change the Reading

Acid-reducing medicines such as PPIs (for example omeprazole), H2 blockers, and antacids can raise the stomach’s reading.21The Royal Children’s Hospital Melbourne. Nasogastric and Orogastric Tube Insertion and Management That is one reason a high reading doesn’t prove the tube is misplaced, yet it still means you don’t feed.

Feeds do something similar. Feed in the stomach soaks up some acid for a time afterwards. In critically ill infants, 97% of stomach samples read 5.5 or below when there were no recent feeds or acid-reducing medicines, compared with 67% shortly after a feed.22PubMed. The pH of Feeding Tube Aspirates From Critically Ill Infants Testing just before a feed is due, rather than straight after one, gives the clearest result.

You can plan around this. Ask your team whether a dose time could be moved before the check, and keep a record of your usual readings. A reading that is often high is something to raise with your nurse.

Keeping the Tube Safe Between Checks

Keep the head and shoulders raised to at least 30 degrees during a feed and for an hour afterwards.23Right Decisions SCOT NHS UK. Enteral Feeding – Nasogastric Tube Sitting up helps feed drain onward from the stomach and stops it flowing back up into the food pipe.24Right Decisions SCOT NHS UK. Enteral Feeding – Nasogastric Tube Pillows or an adjustable bed help, but slumping down in bed reduces the angle. If you need to lie flat for a short time, pause the feed first and ask your team how long to wait before restarting.

Check the tape on the nose every day and make a note of the marking where the tube leaves the nose. Keep a child’s hands away from the tube.

Coughing, choking, or breathing trouble during a feed can mean the tube is in the wrong place. Stop the feed straight away and get urgent help. In UK hospitals, feeding through a misplaced tube that wasn’t caught beforehand counts as a “never event”, the most serious category of preventable error.25HSSIB. Investigation report: Placement of nasogastric tubes

How Long Aspirating Takes and What Changes With Practice

The check itself takes a few minutes, but roughly 3 in 10 checks may not confirm placement on the first attempt when people take acid-reducing medicines or can’t swallow.26PubMed. Confirmation of nasogastric tube position by pH testing Leave time for a wait before a feed is due. Checking about 20 minutes ahead gives room for a repeat without a long delay. If medicines are time-critical, ask your team how to plan for this.

A steady routine helps. Keep a spare syringe and extra strips with the feeding equipment so you don’t have to search when a check goes wrong. Keep strips dry and in date, and put the record sheet in the same place so you write each reading down straight away. Use the same steps in the same order every time.