Capnography facilitates blind nasotracheal intubation.

Continuous capnography recordings were made during blind nasotracheal intubation of 17 patients breathing spontaneously. The carbon dioxide analyzer (CD 300, Datex Helsinki) was connected to the open proximal end of the endotracheal tube. In addition to the auscultatory findings, capnography gave valuable information about the position of the endotracheal tube during the entire intubation procedure. The low and peaked CO2 waves recorded from the nasopharynx tended to become higher and more flat-topped as the larynx was approached. When the tip of the endotracheal tube erroneously glided behind the larynx (12 of the 17 cases) this was promptly revealed by absence of CO2 in the recording. On the other hand, entrance of the tube into the trachea could always be rapidly detected as typical flat-topped CO2 waves were seen in the capnogram. Thus capnography facilitates orientation during blind nasotracheal intubation and rapidly detects accidental oesophageal intubation. The capnographic recording also is a valuable and reliable additional sign and document of correct endotracheal intubation.