A co-oximeter can provide a measurement of all hemoglobin variants, while a pulse oximeter can only measure functional hemoglobin. Why does a pulse oximeter only measure functional hemoglobin?

Question

Quizplus · Accepted Answer

A pulse oximeter uses two wavelengths of light to measure functional hemoglobin, specifically oxyhemoglobin and deoxyhemoglobin, which are the two main forms of hemoglobin found in arterial blood. It is not designed to detect other hemoglobin variants, such as carboxyhemoglobin or methemoglobin, which can be detected by a co-oximeter. The choice "none of the above" is incorrect because the number of wavelengths used is relevant to the question.

A Co-Oximeter Can Provide a Measurement of All Hemoglobin Variants