Final answer:
A pulse oximeter is a device used to measure the oxygen saturation level in the blood, typically placed on the fingertip or earlobe, and provides readings essential for assessing metabolic rate and detecting medical conditions related to oxygen levels in the blood.
Step-by-step explanation:
The device that is placed on the patient's fingertip or earlobe to measure the amount of oxygen in the peripheral blood is called a pulse oximeter. This device functions by emitting two different wavelengths of light, red and infrared, through the body part and measuring the change in light absorption using a photodetector. The differences in the absorption of these wavelengths by hemoglobin, depending on its oxygen saturation, allow the pulse oximeter to provide a reading of the percentage of oxygen saturation in the blood, which is normally between 95-100 percent. Lower percentages can indicate hypoxemia or hypoxia, signaling potential medical issues or the need to assess a person's metabolic rate, which relates to how food energy is converted to other forms in the body.