Comparison of a self-inflating bulb syringe and a colorimetric CO₂ indicator with capnography and radiography to detect the misdirection of Naso/Orogastric tubes into the airway of critically ill adult patients

OBJECTIVE: The objective of this study was to develop a mechanism of discovering misdirection into the airway of naso/orogastric (NG) tubes before they reach their full depth of placement in adults. METHODS: A prospective, observational study was performed in humans, evaluating both the self-inflating bulb syringe (SIBS) and a colorimetric CO₂ detector. A prospective convenience sample of 257 NG tube placements was studied in 199 patients in medical ICUs of a tertiary care medical center. Findings were compared to a "standard" (ie, end tidal CO₂ results of a capnograph and the results of a chest radiograph performed at the completion of the tube placement). RESULTS: On the first tube placement attempt in any patient, the SIBS had a sensitivity of 91.5% and a specificity of 87.0% in detecting nonesophageal placement, while the colorimetric device exhibited 99.4% sensitivity and 91.3% specificity. On subsequent insertions, the SIBS showed 95.7% sensitivity and 100% specificity, while the colorimetric device exhibited 97.8% sensitivity and 100% specificity. The colorimetric device was eight times more expensive than the SIBS. CONCLUSIONS: The SIBS and the colorimetric CO₂ detector are very good at detecting NG tube malpositioning into the airway, although the colorimetric device is slightly more sensitive and specific. Neither method adds substantial time or difficulty to the insertion process. The colorimetric device is substantially more expensive. The decision as to which method to use may be based on local institutional factors, such as expense.