Verification of endotracheal tube misplacement with the colorimetric carbon dioxide detector during anesthesia

The sensitivity and reliability of the colorimetric end-tidal carbon dioxide detector (CETCO2) in verifying misplacement of endotracheal tube in the esophagus were assessed during induction of anesthesia using a conventional capnograph as control. Sixty patients of ASA physical status I and II undergoing elective minor surgery had their anesthesia induced with thiopental sodium (4-5 mg/kg, i.v.). Oral endotracheal intubation facilitated with succinylcholine (1.0 mg/kg, i.v.) was performed by junior residents. The time required for the appearance of discoloration from purple (< 2.5 torr) to tan-hued (3.8-7.6 torr) or yellow (> 15.2 torr) on the CETCO2 (T1) was significantly shorter (3.83 +/- 0.92 second vs. 8.23 +/- 1.14 second, p < 0.01) as compared with the initial display of the ETCO2 waveform on the capnograph (T2). Out of 60 patients esophageal intubation occurred in 6 (10%). Two patients had the color of the CETCO2 changing from purple to tan-hued at the first breath but reverting to purple at the 2nd or 3rd breath. Thus, the sensitivity of CETCO2 was 97.0% (3.0% false positive) if the first breath was chosen as the point of determination. However, if it was set at the 6th breath or yellow was chosen as the color of determination, the sensitivity increased to 100% without either false positive or false negative. In conclusion, the CETCO2 detector is reliable for the detection of correct placement of endotracheal tube during induction of anesthesia, no matter whether Jackson-Rees modification Ayre's T-piece or anesthetic breathing circuit is used for ventilation.