Evaluation of an end-tidal carbon dioxide detector in the aeromedical setting

Endotracheal intubation is a lifesaving technique performed by flight crews often under difficult circumstances. Inadvertent unrecognized esophageal intubation is reported to occur up to 8% of the time. Recently a new disposable device has been developed to assist in determining proper endotracheal tube placement. The FEF end-tidal carbon dioxide detector (Fenem Co.) was evaluated in this study. From June 1989 to January 1990, all patients intubated or transported with endotracheal tubes in place by LifeStar, helicopter Emergency Medical Service, had the FEF detector positioned on the endotracheal tube. Flight crews continuously monitored changes in the indicator of the FEF during transport. On arrival to the emergency department, tube position was verified with direct laryngoscopy by an emergency department physician or trauma surgeon. Thirty-five patients were entered into the study. Thirty-four were identified by direct laryngoscopy as having proper placement of the their endotracheal tube and one was found to be intubated in the esophagus. The FEF device properly identified the single esophageal intubation and accurately identified proper position of the endotracheal tube in thirty-two patients. Of the three patients in cardiopulmonary arrest, the FEF device was accurate in detecting tube position in each case. The overall sensitivity of the FEF detector in this aeromedical setting was 94%. Specificity was calculated as 100%. The overall positive predictive value of the FEF detector was 100%. We therefore conclude that indication of a tracheal intubation by the FEF detector is reliable after six breaths in the aeromedical setting and advocate its use as an adjunct for monitoring tube position while in flight.