Objective: To investigate the effectiveness of capnometry (carbon dioxide monitoring) in verifying gastric placement of a stylet-guided nasogastric tube in intubated, mechanically ventilated patients.
Design: A prospective descriptive study.
Setting: Fourteen-bed medical-surgical intensive care unit, 11-bed coronary care unit, and 18-bed chronic ventilator unit in a 700-bed teaching hospital.
Patients: A total of 53 adult patients on mechanical ventilation and enteral feedings.
Interventions: After the feeding tube was inserted to 30-cm length and before the first chest roentgenogram was taken, the end-tidal carbon dioxide detector was attached to the proximal end of the feeding tube. It was left in place for 1 min and was observed for a change in color (originally purple, it will turn tan or even yellow on contact with carbon dioxide). If the end-tidal carbon dioxide detector remained purple, it was interpreted as gastrointestinal placement; if it turned tan or yellow, it was interpreted as airway placement. The first chest roentgenogram was taken to confirm observations made with the end-tidal carbon dioxide detector. The feeding tube was advanced and a final chest roentgenogram verified its position below the diaphragm.
Measurements and main results: In 52 of the 53 placements, no carbon dioxide was detected. The position in the gastrointestinal tract was confirmed by the two-step procedure. There were no false positives; the technique was 100% specific. One placement out of the 53 was found to be in the trachea. The end-tidal carbon dioxide detector appropriately detected carbon dioxide. This indicated no false negatives. To verify the sensitivity, 20 placements were made directly into the trachea through an endotracheal tube. In all 20 cases, carbon dioxide was detected. No false negatives occurred, indicating 100% sensitivity. Testing in spontaneously breathing patients was not conducted.
Conclusions: Capnometry is a safe method for verifying proper feeding tube placement. The first chest roentgeno-gram can be safely eliminated. With this method, less time and money will be expended in feeding tube placement, making capnometry an efficacious new method.