Combined use of the esophageal-tracheal Combitube with a colorimetric carbon dioxide detector for emergency intubation/ventilation

J Clin Monit. 1995 Sep;11(5):311-6. doi: 10.1007/BF01616989.


Objective: The esophageal-tracheal Combitube (Sheridan, Inc., Argyle, NY) is a unique double lumen tube that has been introduced as an emergency intubation device. Since it is placed blindly, proper use requires determination of which lumen can be successfully used for ventilation. The Easycap (Nellcor, Inc., Pleasanton, CA) is a colorimetric carbon dioxide detector that reacts with exhaled gas to indicate proper tracheal tube location. The purpose of this study was to determine if the Easycap can be used to identify which Combitube lumen is patent to the trachea after blind placement in dogs.

Methods and results: The study was conducted using 8 anesthetized dogs. In each of 15 blind insertions of the Combitube, the Easycap device responded appropriately by changing color from purple to yellow when connected to the lumen communicating with the trachea. When the Easycap device was connected to the alternate lumen, no color change was appropriately observed in 9 out of 15 cases (60%) after 6 breaths; in 4 of the remaining 6 (87%, total), no color change was noted after 12 breaths. In the 2 remaining cases, the color change indicated the need of further verification of the tube location. In separate experiments, 10 direct tracheal and esophageal insertions of the Combitube were correctly verified by the appropriate Easycap color change.

Conclusions: Our results suggest that the Easycap device may be useful with the Combitube, although human data are required.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Carbon Dioxide / analysis*
  • Colorimetry / instrumentation*
  • Dogs
  • Emergency Medical Services
  • Female
  • Intubation, Intratracheal / instrumentation*
  • Male
  • Respiration, Artificial / instrumentation*


  • Carbon Dioxide