What is the primary use of a colorimetric CO2 detector?

The primary use of a colorimetric CO2 detector is to confirm tracheal placement of an endotracheal tube (ETT). When the ETT is properly positioned in the trachea, the presence of exhaled carbon dioxide (CO2) will result in a color change in the detector, indicating that the tube is in the correct location. This is crucial in emergency situations where rapid confirmation of tube placement is essential to ensure adequate ventilation and oxygenation of the patient.

Monitoring ventilation and measuring arterial blood gases, while they relate to the overall assessment of a patient's respiratory status, do not specifically involve the immediate confirmation of endotracheal tube placement. Similarly, assessing cardiac output pertains to a different aspect of patient monitoring that does not involve the direct evaluation of CO2 levels in the airways. Thus, the use of a colorimetric CO2 detector is specifically focused on verifying that an ETT is correctly placed in the trachea, making this answer the most accurate in the context of the question.