• J J Kelly, C A Eynon, J L Kaplan, L de Garavilla, and W C Dalsey.
• Department of Emergency Medicine, Albert Einstein Medical Center, Philadelphia, PA, USA.
• Ann Emerg Med. 1998 May 1;31(5):575-8.

Study ObjectiveTo determine whether condensation on the inner surface of the endotracheal tube (vapor trail) is a reliable indicator of intratracheal placement.MethodsTwenty-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 tube was then placed in the esophagus. An attending emergency physician, blinded to tube placement, then used a bag-valve apparatus to manually ventilate each endotracheal tube in turn. Five ventilations were performed on each tube, and the presence or absence of condensation on the 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.ResultsVapor trail was observed in 27 (100%) of 27 endotracheal tubes correctly placed 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%). Physicians concurred in all cases. Absence of vapor trail was 15% sensitive (95% CI, 4% to 34%) for indicating incorrect (esophageal) tube placement.ConclusionIn this model, condensation on the inner surface of the endotracheal tube was common after placement within the esophagus. If these results are confirmed in human studies, the presence of a vapor trial should not be used as a clinical indicator of correct endotracheal tube placement.

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