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Updated: Jun 24, 2026

Evaluation of Capnography Sampling Line Compatibility and Accuracy when Used with a Portable Capnography Monitor
Published on: September 29, 2020
Colorimetric capnography to ensure correct nasogastric tube position
Pascal Meyer1, Matthieu Henry, Eric Maury
1Service de Réanimation Médicale, Hôpital Saint-Antoine, Assistance Publique-Hôpitaux de Paris, 75571 Cedex 12 Paris, France.
Purpose:
We evaluate a procedure, combining colorimetric capnography with epigastric auscultation, to ensure nasogastric (NG) feeding tube correct position without any radiograph.
Methods:
We first evaluated the accuracy of colorimetric capnography in detecting tracheal positioning in a control group of 100 mechanically ventilated patients. The procedure was thereafter evaluated in a study group including patients requiring an NG tube. The NG tube was first inserted 30 cm and connected to a colorimetric capnograph (first step). If the capnograph did not detect carbon dioxide, insertion was completed to a total distance of 50 cm. An epigastric auscultation after air insufflation and a second capnography (second step) were performed. A radiograph evaluated correct tube position.
Results:
In the control group, colorimetric capnograph sensitivity to detect tracheal placement was 100%. In the study group, negative predictive value of first-step capnography to rule out tracheobronchial insertion was 100%. The association of a first-step negative capnography with a positive epigastric auscultation correctly identified all but one gastric insertions, yielding a sensitivity of 98.5% (95% confidence interval, 95.7-100). The positive predictive value of this association to detect gastric placement was 100%.
Conclusion:
Colorimetric capnography combined with epigastric auscultation is safe and accurate in ensuring correct gastric tube insertion.
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