Which device provides a color change to indicate exhaled CO2 during intubation?

• A. Waveform capnography
• B. Pulse oximetry
• C. Colorimetric end-tidal CO2 detector
• D. Laryngoscope

Answer: (C)

A colorimetric end-tidal CO2 detector provides a color change to show exhaled CO2. It contains a dye that reacts to CO2 and shifts color (usually purple to yellow) when air exhaled from the lungs passes through it. This quick visual cue confirms that the endotracheal tube is in the trachea, since correctly placed tubes deliver CO2 to the device. If the tube is in the esophagus, little or no CO2 is delivered and the color does not change. This is different from waveform capnography, which displays a CO2 waveform and numeric ETCO2 values on a monitor; pulse oximetry measures oxygen saturation, not CO2; and a laryngoscope is used for visualizing the airway, not for CO2 indication.