A 76-YEAR-OLD PATIENT experienced complications from a misplaced nasogastric (NG) tube that ultimately cost him his life. He was admitted to the hospital following the diagnosis of a spontaneous intracerebral hemorrhage. He experienced left-sided hemiplegia and dysphagia that required enteral nutrition (EN) through an NG tube. Nurses used the auscultatory (air bolus) method to determine the NG tube location by listening over his epigastrium for air insufflated through the feeding tube every 4 hours. Four weeks later, the patient developed signs and symptoms of sepsis. Computed tomography identified diffuse gastric submucosal emphysema and a possible gastric perforation. Despite treatment, the patient died 3 days later as a direct result of NG tube misplacement in the gastric mucosa and possible gastric perforation, leading to severe sepsis.1
Nurses are responsible for using a valid assessment method to ensure that an NG tube is placed correctly before each use. Nurses who understand the validity and limitations of each assessment method can prevent life-threatening complications and even death, as this case illustrates. This article reviews evidence-based methods for assessing NG tube positioning and the limitations of each method.
Intended for short-term use
Used for administration of short-term EN and other therapies, NG tubes are flexible single- or double-lumen tubes passed proximally from the nose to the stomach. Similarly, orogastric tubes can be passed from the mouth to the stomach to deliver short-term therapies.2 For the purpose of this article, the term NG tube will be used to include both types of short-term feeding tube.
NG tubes are used in everyday nursing practice for gastric emptying, EN, and medication administration. Patients may require an NG tube for a few days to as long as 3 weeks. After blindly placing an NG tube, the provider confirms placement with a radiograph of the lower chest/upper abdomen (abdominal radiograph).3
Misplaced NG tubes are associated with many potentially serious complications, such as gastric perforation, pulmonary abscess, pneumothorax, gastritis, gastric ulcer, and gastric reflux.2,3 The Joint Commission has identified pulmonary malposition of NG tubes as one of the most frequent procedural complications resulting in sentinel events.4 Besides the lung, these temporary tubes can be misplaced into the mediastinum, cranial cavity, spinal canal, great vessels, and right atrium.1,3 Minimizing placement errors during insertion and ongoing use reduces the complication rate and improves patient outcomes.2,5
However, even when an NG tube is positioned properly during initial placement, it may become dislocated during use.3 In fact, NG tubes can migrate proximal to the initial placement site with coughing, suctioning, vomiting, repositioning the patient, ambulation, and failure of the securement method or device. Consequently, tube position must be reconfirmed frequently for as long as the tube is in place.
Confirm initial placement
Research demonstrates that it is not uncommon for NG tubes to be misplaced on initial insertion. In one study, Sorokin and Gottlieb assessed 2,000 blind small-bore NG tube placements. Over a 4-year period, they found 50 documented cases of malpositioned devices resulting in 13 complications and 2 deaths.6
Abdominal radiographs are accurate methods of confirming correct placement of a blindly inserted small-bore or large-bore tube before its initial use for feedings or medication administration.3,7 Electromagnetic tube placement (ETP) devices may also provide reliable information. Using an electromagnetic stylet, an ETP device provides real-time location information on tube tip placement within a patient's anatomy.
Investigating the rate of agreement between clinician interpretation of small bowel feeding tube placement using the ETP images and X-ray confirmation, Carter and colleagues found that ETP images and radiographs were in agreement with 86% to 99.5% accuracy, depending on the expertise of the clinician using the ETP device.8 However, reliable use of an ETP device depends on the practitioner's experience, skill, and familiarity with the equipment. The American Association of Critical-Care Nurses (AACN) currently recommends radiographic confirmation of tubes inserted with ETP assistance.3
Assessment standards for nurses
Based on current guidelines, nurses must reassess tube placement every 4 hours and before administering EN or medication.3,9 Although abdominal radiographs are the gold standard, performing radiographs repeatedly to confirm tube position is not practical or cost-effective and also exposes the patient to unwanted radiation.9 Nurses must rely on secondary methods for frequent bedside confirmation of continued correct placement. These methods are research-based, taught in nursing schools, and used by nurses to verify placement without additional cost or unnecessary exposure of the patient to radiation.
However, research has revealed that some once-common methods should no longer be used—specifically, the auscultatory (air bolus) method and the bubbling method, both of which were taught to generations of nurses. The auscultatory method involves listening over the epigastrium for air insufflated through the feeding tube. The bubbling method involves holding the proximal end of a feeding tube under water and observing for bubbles upon exhalation.3
Neither of these methods is considered valid today based on three studies conducted between 1988 and 2007.5 All three studies showed that nurses were unable to distinguish variations in the sound of an air bubble entering the lungs, esophagus, stomach, or small intestine, and little research has been conducted to investigate the accuracy of the bubbling method. Continued research in 2014 and 2017 supported previous research showing that these methods are not accurate and that relying on them jeopardizes patient safety. Neither method should be used to assess tube placement.3-5,9
Current research supports the use of abdominal radiographs to confirm initial correct placement of blind insertions. Immediately after radiographic confirmation, mark the tube's exit site from the nose or mouth and document the incremental length (the number found on the tube in cm) also at the nose or mouth. Any change in the length of the external portion of the tube will alert clinicians to possible tube migration.3
For ongoing assessments every 4 hours and before administration of medications and EN, the AACN recommends that nurses use at least two of the following bedside methods:3
- Observe for signs of respiratory distress. Coughing, choking, and dyspnea may indicate that the tube is in the airway. However, not all patients experience respiratory distress, especially those with a decreased level of consciousness.
- Use capnography, if available, to detect any release of carbon dioxide from the tube. This would suggest placement in the tracheobronchial tree rather than the stomach. To perform this simple test, the nurse attaches a carbon dioxide detector to the end of the tube. A color change on the detector indicates whether carbon dioxide is present. Any feeding should be stopped immediately and an X-ray obtained to investigate.
This method can be especially valuable for detecting tube malposition in patients who do not have any signs or symptoms of tube misplacement in the pulmonary tract. However, it also has limitations. For example, capnography cannot distinguish between placement in the esophagus and the stomach.5 A tube that migrates into the esophagus places the patient at increased risk for aspiration.
The literature does not contain significant research to support the accuracy of using this method to assess the placement of the tube every 4 hours. In addition, this method is limited by the availability of carbon dioxide detecting devices.
- Measure the pH of tube aspirate with pH strips. The fasting pH of gastric fluid is usually 5 or less and the pH of both respiratory and small bowel secretions is typically 6 or more. But the reliability of pH testing has limitations. For example, it cannot be used to distinguish between gastric and esophageal placement because pH is altered if the aspirated fluid is mixed with saliva or gastric reflux.3 In addition, the pH of tube feeding is a base, which increases the pH of gastric aspirate. Therefore, in order to ensure reliable results from a pH test, tube feeding should be stopped for 1 hour before testing.3 However, if a continuous tube feeding is stopped for 1 hour every 4 hours to verify placement, the patient would lose 6 hours of feeding every day. For a patient who requires continuous EN, this is not acceptable.
Another factor influencing the usefulness of this method is the nurse's ability to aspirate fluid from the tube. According to one estimate, fluid can be aspirated from only about 85% of tubes, and this fluid could originate in either the gastrointestinal tract or the lungs.10 In addition, some hospital protocols prohibit aspiration of small-bore feeding tubes for testing gastric residuals and tube placement.
For accurate interpretation of pH testing, nurses must know normal pH values in the lungs and in various areas of the GI tract, as well as consider many factors that can influence the results and limit the test's accuracy.
- Assess the appearance of aspirate from the tube if feeding has been interrupted for at least an hour. Distinguishing gastric and pulmonary fluids can be difficult, but a visual assessment may provide evidence that the tube has moved from the stomach to the small bowel: Gastric fluid is usually clear and colorless or green, whereas small bowel fluids are likely to be bile-stained.3
If bedside methods suggest that a tube is out of place, request an X-ray to investigate.
Marking and assessing exit sites
As noted previously, the AACN recommends marking and documenting the exit site of the tube or the documented incremental length of the tube at the time of radiographic confirmation of correct placement. At 4-hour intervals, the nurse should observe for any change in the length either by marked area on the external length of the tube or the incremental number previously documented, suggesting migration.
As with other methods, however, this has potential limitations. For example, some electronic documentation systems have no place to document either of these lengths, which could lead to miscommunications.
As a clinical nurse for many years, I once used the now-discredited methods discussed above to check the placement of gastric tubes. Based on what the evidence shows, I have since turned to documenting the incremental length of the tube. The electronic health record that is used in my facility can document this length. My peers also use this method, which allows for more accuracy.
As a nursing instructor for prelicensure nursing students, I have also started teaching the use of incremental length as well as the use of monitoring the marking of the external length. Using this method, one of my students was able to identify that a patient's tube had migrated based on a change in the incremental length. The patient's tube feeding was stopped and the provider ordered an X-ray, which confirmed that the position of the tube had migrated out of the stomach. This assessment prevented complications for the patient.
Healthcare facilities maintain research-based protocols that include safe and accurate methods to guide practice and maintain patient safety. Clinical nurses who understand the why, when, and how for maintaining correct gastric tube placement can protect patients from complications and even save a life.
Follow best practices: A summary3
The American Association of Critical-Care Nurses recommends the following best practices for initial and ongoing verification of feeding tube placement in adults.
- Use at least two of the following bedside methods to assess tube location during the insertion procedure: assess for respiratory distress, use capnography if available, test pH aspirate from the tube, and observe the appearance of aspirate from the tube.
- Do not use the auscultatory (air bolus) or water bubbling method to determine tube location.
- Confirm correct placement with an X-ray following blind insertion of a feeding tube before using it for feeding or medication. The X-ray should show the entire length of the tube and be interpreted by a radiologist.
- Mark and document the tube's exit site from the patient's nose or mouth as soon as an X-ray confirms correct placement.
- Check tube location at 4-hour intervals after feedings begin. Assess for any change in the length of the tube's external portion and recommend X-ray confirmation if its position is questionable.
- Observe aspirate for changes in volume.
- If feedings are interrupted for an hour or more, observe the appearance of feeding tube aspirate and measure aspirate pH with pH strips, if available.
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