A noninvasive monitor that estimates arterial blood HbO2 saturation is known as what?

The correct answer is the pulse oximeter, which is a noninvasive device used to estimate the arterial blood hemoglobin oxygen saturation (HbO2). This device works by using light absorption characteristics of oxygenated and deoxygenated hemoglobin. Typically, it involves placing a sensor on a thin part of the body, like a fingertip or earlobe, where it emits light and detects how much light is absorbed by the blood vessels. This information is then processed to provide a percentage reading of oxygen saturation, which is crucial for assessing a patient's respiratory status and ensuring they are receiving adequate oxygen.

In contrast, a capnometer measures the concentration of carbon dioxide in exhaled air and is primarily used to assess ventilation rather than oxygen saturation. A sphygmomanometer is used to measure blood pressure, and an electrocardiogram records the electrical activity of the heart. None of these monitors provide data on arterial blood oxygen saturation in the manner that a pulse oximeter does. Thus, the pulse oximeter stands out as the appropriate tool for this specific function in respiratory care.