Verifying nasogastric tube placement

[tkyeung]

I have been taught that to verify the correct placement of a nasogastric tube, we should check the pH of aspirate obtained. I wonder if a patient has gastric content aspirated into trachea or lower respiratory tract silently, and I misinsert the nasogastric tube into his trachea, then the pH obtained would still be less than 5.5? Then I would mistook the placement as correct, which in fact is not. Is it possible that this situation would occur?

[TU RN, DNP, CRNA]

CXR is the best (should be the only) way NG tube placement is confirmed and the thing shouldn't be touched until one is obtained and interpreted by a physician. Risk of drowning somebody in their lactulose is *slightly* greater than the cost of a CXR, methinks.

[tkyeung]

That means I should make sure that the patient has no pulmonary aspiration before I insert the nasogastric tube in order to avoid the scenario I described above?

[TU RN, DNP, CRNA]

Whether the person has aspirated or not, a chest radiograph will confirm the location of the tip of a nasogastric tube in the stomach, trachea, or left/right bronchial stem. Where I work not only are nurses not required to insert NG tubes, but nobody uses litmus paper for placement confirmation. As far as I know this is antiquated and done with. If you put an NGT into somebody's lung, unless they are comatose or sedated, they'd be in distress.

To directly answer your question, "is this possible?", I don't know. If I had to make an educated guess I'd say you'd need 2 scenarios: 1) where there is so much gastric residual in the lung that the person is critically ill or 2) where you've inserted a NGT so deep into a persons lung that they are now critically ill.

[ICU56]

Ive never checked pH, its policy that NG tubes are confirmed by CXR before use. I dont know if any aspirate would cause the situation you described, but if I was relying on that method of checking placement and couldn't CXR I would use all the non XR methods before even considering using it, capnography etc. Even then I would be cautious.

[tkyeung]

That means i have to rule out pulmonary aspiration of gastric content, e.g. vomitus, before i use pH method to verify N/G tube placement?

[MunoRN, RN]

Best practice has generally transitioned to radiographic confirmation of feeding tube placement (X-ray, flouro, CT etc). Aspirate pH, auscultation and CO2 detection are still used but usually just to rule out obvious malposition prior to imaging.

So you don't really have to rule out aspiration since you really shouldn't be using pH as the definitive confirmation of placement anyway.

[TU RN, DNP, CRNA]

You must rule out pulmonary aspiration of gastric content before using the pH method to verify NG tube placement.

This seems like a homework question (your profile lists you as a nursing student, dead giveaway), but I assure you in real life NG tubes aren't checked by litmus paper. Maybe one day in the past, I wouldn't know, but not now.

[tkyeung]

I have found on the Internet that when gastric contents are aspirated into respiratory tract, the tract is irritated and there will be exudation of fluid that neutralizes the aspirate. Then the pH of the mixture will be more higher/ alkaline. Is it true?

[tkyeung]

And our school textbooks told us that if pH obtained is less than or equal to 5.5 then the tube reaches the stomach