Prior to using a nasogastric tube (NG) it is essential to check that it is in the correct position and that the tube has not moved or become displaced. This can happen easily and the tube position should be checked regularly and prior to administration of anything. Ensure a referral has been made to the dietitian for prescription of a suitable feeding regimen.
Once tube position has been confirmed feeding can be commenced as per Dietetic regimen or out of hours protocol.
NB: Be aware that certain medications can inhibit or reduce gastric aspirate production e.g. Omeprazole, Lansoprazole.
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- If aspirate pH ≤ 5.5 it is safe to use the nasogastric tube.
- If aspirate pH is ≥ 5.5 do not use the tube, review medications and retry in 15-30mins.
- If no aspirate available or obtained it is not safe to use the nasogastric tube. The tube can easily migrate or become twisted within the body causing it to have moved to an area where there is the risk of aspiration – this can happen through vomiting/coughing up the tube or even through turning a patient. Refer to your local polices for trouble shooting-guidelines.
- It is recognised that obtaining an aspirate from fine bore tubes can be difficult. Correct syringe size, insufflating before aspirating, changing position, teeth brushing can all help with achieving aspirate.
Auscultation of air into the stomach
In 2005, the National Patient Safety Agency (NPSA) banned the use of this (also known as the whoosh test) in health boards in England and Wales. Many health boards in Scotland have followed suit – check your local policy for further information. In some areas this test is still carried out e.g. by medical practitioners due to lack of reliable alternatives if an aspirate cannot be obtained, for example, if the patient is prescribed an acid suppressing drug, and the risk to the patient of not being fed or administered vital medications is felt to be considerable.
Observing for respiratory symptoms
if Bill is not coughing, choking or is cyanosed it does not mean that the tube must be in the stomach.
Visual inspection of aspirate
It is difficult to tell the difference between gastric aspirate (may be green, tan or brown) and respiratory aspirate (may be tan or yellow).
Using litmus paper
Litmus paper will only check if aspirate is acid or alkali and is not an accurate method to detect gastric or respiratory aspirate.
Using pH paper
The correct pH is between 1.0 and 5.5. Use pH paper, not litmus paper as litmus paper cannot detect the difference between gastric aspirate (pH 1-6) and bronchial secretions (pH 5.5-7).
Taking an X-ray
This is not usually first choice but may be used for certain at-risk patients e.g. those with altered consciousness or receiving ventilation or when an aspirate cannot be obtained. Still carries some risk although it is our most reliable method.
Electromagnetic tracking system
This is a new device with an electromagnetic stylet on the tube that transmits a signal. This signal is detected by a receiver which displays the movement of the feeding tube as it passes down the oesophagus and into the stomach.
Page last reviewed: 02 Jun 2021
