Capnography for detection of accidental oesophageal intubation.

The clinical diagnostic signs for detecting inadvertent oesophageal intubation may all be misleading. We therefore tested the practice of recording exhaled carbon dioxide during the intubation procedure as an additional measure for detection of accidental oesophageal intubation. Twenty patients were intubated simultaneously into the trachea and oesophagus and the carbon dioxide concentration was continuously recorded from both sources. Manual ventilation of the lungs always resulted in a typical CO2 curve pattern. Ventilation by mask prior to the intubation obviously resulted in some filling the stomach by exhaled gas in 9 of the 20 patients. In these cases some CO2 could be detected during oesophageal ventilation. As the oesophageal CO2 concentrations were very low initially, compared to the tracheal recordings, and carbon dioxide completely disappeared after a few ventilations into the oesophagus, distinguishing between the tracheal and oesophageal capnography tracings was easy.