 Ideally , at least one of the methods utilized for confirming tracheal tube placement will be a measuring instrument . <unk> <unk> has emerged as the gold standard for the confirmation of tube placement within the trachea . Other methods relying on instruments include the use of a colorimetric end @-@ tidal carbon dioxide detector , a self @-@ inflating esophageal bulb , or an esophageal detection device . The distal tip of a properly positioned tracheal tube will be located in the mid @-@ trachea , roughly 2 cm ( 1 in ) above the bifurcation of the carina ; this can be confirmed by chest x @-@ ray . If it is inserted too far into the trachea ( beyond the carina ) , the tip of the tracheal tube is likely to be within the right main bronchus — a situation often referred to as a " right mainstem intubation " . In this situation , the left lung may be unable to participate in ventilation , which can lead to decreased oxygen content due to ventilation / perfusion mismatch . 
