Nasogastric tube placement

Anasogastric tube is sited in a patient ventilated on the critical care unit.Which one of the following is considered the MOST ACCURATE way of confirming correct positioning?

a) Measurement of the aspirate using pH indicator strips

b) Auscultation of air insufflated through the nasogastric tube (the ‘whoosh’ test)

c) Testing the acidity/alkalinity of aspirate fromthe nasogastric tube using litmus paper

d) Observing the appearance of the aspirate from the nasogastric tube

e) Chest radiograph

Answer: e

Explanation:

There have been a number of safety alerts involving the misplacement of nasogastric

tubes. The only two recommended methods for confirming correct nasogastric tube

placement are chest radiography and the use of pH indicator strips or paper. No other

methods including the other three options listed in the question are considered safe.

The most accurate method for confirming correct tube placement is accurately reported

chest radiography. However, there have been multiple reports of X-rays being misinterpreted

and minimising X-ray exposure is also important, particularly in the

critically ill patient. pH testing may be influenced by co-administration of medication

that could elevate the pH level of gastric contents, e.g. antacids, H2 antagonists and

proton pump inhibitors. There are no known reports of pulmonary aspirates with a pH

of less than 5.5 so this is a useful cut-off point. If the pH is greater than this then one

should wait an hour then re-check, as the commonest reason for a higher pH is

the presence in the stomach of enteral feed. The gold standard is radiography. In

addition to following insertion, nasogastric tube position should be re-checked before

administration of feed, at least once daily during continuous feed, following episodes

of vomiting, retching or coughing and if there has been any evidence of tube

displacement.

Reference

National Patient Safety Agency. Reducing the harm caused by misplaced nasogastric

feeding tubes. Patient safety alert 05. NPSA, 21 February 2005. Online at www.npsa.

nhs.uk (Accessed 30 October 2009)