Which device indicates CO2 by color change rather than numeric values?

Which device indicates CO2 by color change rather than numeric values?

• A. Colimetric Device
• B. Capnography
• C. Pulse Oximeter
• D. Spirometer

Answer: (A)

The main idea here is distinguishing devices that give a qualitative color cue for CO2 from those that provide a numeric CO2 reading. A colorimetric CO2 detector uses a chemical indicator that changes color in the presence of CO2, usually signaling with a shift from purple to yellow. This gives a quick, visual confirmation that CO2 is present, but it does not provide a numeric end-tidal CO2 value. In contrast, capnography measures CO2 continuously and reports a numerical ETCO2 along with a waveform, offering precise values and trends. The other two devices don’t assess CO2 at all—one monitors oxygen saturation, and the other measures lung volumes and airflow. So the device that signals CO2 by color change is the colorimetric detector.

The main idea here is distinguishing devices that give a qualitative color cue for CO2 from those that provide a numeric CO2 reading. A colorimetric CO2 detector uses a chemical indicator that changes color in the presence of CO2, usually signaling with a shift from purple to yellow. This gives a quick, visual confirmation that CO2 is present, but it does not provide a numeric end-tidal CO2 value. In contrast, capnography measures CO2 continuously and reports a numerical ETCO2 along with a waveform, offering precise values and trends. The other two devices don’t assess CO2 at all—one monitors oxygen saturation, and the other measures lung volumes and airflow. So the device that signals CO2 by color change is the colorimetric detector.