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One of our most surprising frequently accessed columns has been our November 1, 2011 Patient Safety Tip of the Week “So What’s the Big Deal About Inserting an NG Tube?”. In that column we noted numerous reports from the UK’s NPSA of incidents and bad outcomes related to NG (nasogastric) tubes and we mentioned some of our own observations.
NG tube insertion is viewed by many as a simple and routine procedure. But we have seen NG tubes in patient’s lungs, the pleural space, and even in a cerebral ventricle! So we have a great respect for proper NG tube insertion.
Then, our October 2016 What's New in the Patient Safety World column “AACN Alert on Feeding Tube Placement” discussed American Association of Critical-Care Nurses press release (AACN 2016) on their practice alert “Initial and Ongoing Verification of Feeding Tube Placement in Adults”. According to that guideline, the expected practice during the insertion procedure is to use a combination of two or more of the following bedside methods to predict tube location:
But, confirmation by radiography is still the most important element but results of the above elements can be used to determine when it is time to use radiography to confirm tube location and they may also be able to reduce the number of confirming radiographs to one. That alert also stressed that nurses should not use the auscultatory (air bolus) or water bubbling method (holding tube under water) to determine tube location.
Now, a new systematic review (Metheny 2019) reviewed guidelines/recommendations to distinguish between gastric and pulmonary placement of nasogastric tubes. The authors identified 14 such guidelines published between 2015 and 2018. Tube placement testing methods included in the review were: radiography, respiratory distress, aspirate appearance, aspirate pH, auscultation, carbon dioxide detection and enteral access devices. All fourteen guidelines agreed that radiography is the most accurate testing method. Of the nonradiographic methods, pH testing was most favored; least favored was auscultation.
Regarding the use of radiography for NG tube placement confirmation, recommendations ranged from ‘always required’ to ‘use only when other methods fail’. But they noted that geographical location influenced whether or not radiography was recommended as the first-line method. Whereas US guidelines favor radiographic testing as the first-line method for tube placement determination, those from Europe and Australia often favor radiographic testing only when the pH-method has failed or patients are ‘at risk’.
Of course, we always observe the patient for signs of respiratory distress after NG tube placement (eg. coughing, choking, tachypnea, cyanosis, etc.) but that should never be a method of determining tube placement. Patients who are obtunded or neurologically impaired may not have such signs even when the tube is in their lungs.
The review discussed that the physical appearance of the NG tube aspirate is not an accurate way of differentiating pulmonary vs. gastric placement. The review then notes considerable variation in the nine guidelines regarding the utility of aspirate pH as a predictor of nonpulmonary placement. Both the reliability of the method and the pH cutoff level vary from guideline to guideline.
Five of the guidelines reviewed discussed the efficacy of carbon dioxide detection devices in distinguishing between gastric and pulmonary placement. All five agree that the method is helpful but insufficient as a sole method to distinguish between gastric and pulmonary tube placement.
Only one guideline referred to auscultation as being sufficient to determine gastric placement. All the others either said auscultation should not be used at all or was unreliable to be used as the sole method of placement determination.
The review also gives little support for use of an enteral access device as a solitary method to distinguish between gastric and pulmonary placement.
The report concludes that there is general consensus among the guidelines that a properly obtained and interpreted x-ray is the most accurate method to distinguish between gastric and pulmonary placement of NG tubes.
Our 2 previous columns include important considerations for the radiologic confirmation of tube location. Our November 1, 2011 Patient Safety Tip of the Week “So What’s the Big Deal About Inserting an NG Tube?” stressed that particular attention be paid to the x-ray requisition, which should clearly state the x-ray is for determination of tube placement. All too often we still see x-ray requisitions filled out with something like the admission diagnosis rather than the real reason for the x-ray. And you need to make sure that the person doing the interpretation is appropriately credentialed to do so (for example, if someone other than the radiologist is doing the interpretation). And feeding should not be commenced via that tube until the radiologist (or appropriately credentialed person) has documented the tube is in the correct location.
Our October 2016 What's New in the Patient Safety World column “AACN Alert on Feeding Tube Placement” noted that correct placement of a blindly inserted small-bore or large-bore tube should be confirmed with a radiograph that visualizes the entire course of the tube prior to its initial use for feedings or medication administration. Once correct tube placement is confirmed, the exit site from the patient’s nose or mouth should be immediately marked and documented to assist in subsequent determinations of tube location. After feedings are started, tube location should be checked at four-hour intervals.
Our original column (November 1, 2011 Patient Safety Tip of the Week “So What’s the Big Deal About Inserting an NG Tube?”) had links to the UK’s National Patient Safety Agency reports that detailed many incidents and complications related to improper NG tube placement. It also had links to a video and other resources on proper placement.
AACN (American Association of Critical-Care Nurses). Feeding Tubes Require Initial and Ongoing Verification to Minimize Complications. American Association of Critical-Care Nurses updates Practice Alert on feeding tube placement. Press Release 15-Sep-2016
AACN (American Association of Critical-Care Nurses). AACN Practice Alert: Initial and Ongoing Verification of Feeding Tube Placement in Adults. CriticalCareNurse 2016; 36(2): e8-e13 April 2016
Metheny NA, Krieger MM, Healey F, Meert KL. A review of guidelines to distinguish between gastric and pulmonaryplacement of nasogastric tubes. Heart & Lung 2019; 48(3): 226-235
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