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Acta Anaesthesiol Sin. 2002 Dec;40(4):159-63.

The tracheal detecting-bulb: a new device to distinguish tracheal from esophageal intubation.

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Department of Anesthesiology, Zhongda Hospital, Southeast University, Nanjing 210009, People's Republic of China.



The tracheal detecting-bulb (TDB) is a diagnostic tool for confirmation of tracheal intubation. Capnography is also accepted as a standard way for such confirmation. The purpose of this investigation was to determine whether the results by TDB agreed with those by capnography.


Four hundred patients were allocated to three separate studies. In 200 consecutive patients of study 1, tracheal intubation was first confirmed with the TDB followed by capnography. In study 2, 100 patients had the esophagus intentionally intubated, and confirmation was performed likewise as in study 1. The tube was then removed, the trachea was intubated, and confirmation tests followed. Study 3 involved 100 patients and was carried out in a double-blind, randomized manner. The tube was intentionally inserted into either the esophagus (n = 42) or trachea (n = 58), and confirmation tests immediately followed.


In study 1, the rhythmic expansion-contraction of TDB was evident in 173 patients, and always agreed with capnographic reading; In 27 instances, the latex bulb of TDB remained collapsed or was scantily filled without the turning-up of capnographic reading as counterchecked, indicating esophageal intubation. In study 2, regardless of esophageal or tracheal intubation, agreement between TDB and capnogram was 100%. In study 3, the agreement between the two detecting instruments was 100% too. In the 400 patients studied, the results from the TDB were in complete accord with those of capnogram. The sensitivity, specificity, and predictive value of the TDB in all of these studies were 100%.


The TDB is a valuable diagnostic technique for confirming tracheal intubation as it could correctly detect esophageal or tracheal intubation of the tracheal tube in all our 400 patients. The results of using TDB agree with the results of using capnography.

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