Which device is used to monitor the oxygen saturation of the blood?

• A. Sphygmomanometer
• B. Stethoscope
• C. Pulse Oximeter
• D. Thermometer

Answer: (C)

Measuring how much oxygen is bound to hemoglobin in the blood is done with a pulse oximeter. This noninvasive device clips onto a finger or earlobe and uses two wavelengths of light to estimate the proportion of hemoglobin carrying oxygen. By comparing how much light is absorbed by oxygenated versus deoxygenated hemoglobin, it provides the SpO2 reading, typically shown as a percentage (often around 95–100% in healthy individuals). This quick, painless monitoring is common in clinics, hospitals, and during anesthesia or emergency care.

The other tools have different purposes: a sphygmomanometer checks blood pressure, a stethoscope lets you listen to heart and lung sounds, and a thermometer measures body temperature.