From the Guidelines
To measure a nasogastric (NG) tube correctly, the most recent and highest quality study recommends measuring from the tip of the nose to the earlobe, then from the earlobe to the xiphoid process, and finally from the xiphoid process to a point midway between the xiphoid and umbilicus, typically resulting in a measurement of 50-60 cm for adults 1.
Key Considerations for NG Tube Measurement
- The measurement should be marked on the tube with tape or noted to ensure accurate placement.
- During insertion, the patient should sit upright if possible, and the tube should be lubricated with water-soluble lubricant and advanced through the nostril while the patient sips water if conscious.
- Proper placement should be confirmed by aspirating gastric contents and checking pH (should be 1-5), or with radiographic verification, which is the gold standard 1.
Importance of Accurate Placement
- Improper placement can lead to serious complications, including aspiration pneumonia if the tube enters the lungs or esophageal trauma if positioned incorrectly.
- Auscultation (listening over the stomach after injecting air) should not be relied upon solely as this method is unreliable 1.
Securing the Tube
- After confirming correct placement, the tube should be secured to the patient's nose with hypoallergenic tape to prevent displacement.
- The use of fine bore (5–8 French gauge) nasogastric tubes is recommended unless there is a need for repeated gastric aspiration or administration of high viscosity feeds/drugs via the tube 2.
From the Research
Measurements for Nasogastric (NG) Tube Placement
- The tip of the nose-earlobe-xiphoid distance (NEX) + 10 cm, with a mean of 59.9-60.7 cm, could potentially result in accuracy as high as 97.4% for correctly positioned NG tubes 3
- The formula (NEX × 0.38696) + 30.37 + 6 cm, with a mean of 56.6-56.7 cm, could potentially result in accuracy as high as 99.0% for correctly positioned NG tubes 3
- XEN (xiphisternum to ear to nose) + 10 cm or more complex measurements may reach the gastric body (mid-stomach) in most patients, but external measurements often fail to predict a safe distance 4
- A tube length of XEN (or NEX) is too short to guarantee gastric placement and is unsafe 4
- The mean insertion distances for NG tubes were: + Pre-gastro-oesophageal junction (GOJ): 48 cm + Gastric body: 62 cm + Gastric antrum: 73 cm 4
Methods for Determining NG Tube Placement
- Colorimetric capnography has been shown to be a valid method for verifying NG tube placement, with a sensitivity of 100% when nasogastric tubes were inserted intentionally into the airways 5
- Capnography has also been shown to detect NG tube position with high accuracy, but further research is required to confirm its effectiveness 5, 6
- Other methods, such as biochemical measurement parameters of feeding tube aspirates (pH, bilirubin, pepsin, and trypsin), have been investigated, but the evidence is limited and does not provide a substantial base for the development of practice guidelines 6