USE OF TUBE CONDENSATION AS AN INDICATOR OF ENDOTRACHEAL-TUBE PLACEMENT

Study objective: To determine whether condensation on the inner surfac e of the endotracheal tube (vapor trail) is a reliable indicator of in tratracheal placement. Methods: Twenty-seven separate experiments were conducted on 10 conditioned, mongrel dogs weighing 15 to 20 kg each. After induction of anesthesia, an endotracheal tube was placed in the trachea under direct visualization. A second, identical endotracheal t ube was then placed in the esophagus. An attending emergency physician , blinded to tube placement, then used a bag-valve apparatus to manual ly ventilate each endotracheal tube in turn. Five ventilations were pe rformed on each tube, and the presence or absence of condensation on t he inner surface of the tube was recorded. A second physician, blinded both to tube placement and to the actions of the first assessor, then repeated the ventilation and assessment of both tubes. Results: Vapor trail was observed in 27 (100%) of 27 endotracheal tubes correctly pl aced in the trachea (95% confidence interval [CI], 90% to 100%) and in 23 (83%) of 27 tubes placed in the esophagus (95% CI, 66% to 96%). Ph ysicians concurred in all cases. Absence of vapor trail was 15% sensit ive (95% CI, 4% to 34%) for indicating incorrect (esophageal) tube pla cement. Conclusion: In this model, condensation on the inner surface o f the endotracheal tube was common after placement within the esophagu s. If these results are confirmed in human studies, the presence of a vapor trail should not be used as a clinical indicator of correct endo tracheal tube placement.