What is the primary purpose of pulse oximetry?

• A. To measure heart rate only.
• B. To assess hydration status.
• C. To monitor arterial oxygen saturation continuously.
• D. To measure blood pressure.

Answer: (C)

Pulse oximetry is used to continuously monitor arterial oxygen saturation in a noninvasive way. By transmitting red and infrared light through a fingertip or earlobe and analyzing how much light is absorbed by oxygenated versus deoxygenated hemoglobin, the device estimates the percentage of hemoglobin carrying oxygen (SpO2) and also provides a pulse rate. This continuous readout is essential for detecting hypoxemia early and guiding oxygen therapy, especially during anesthesia, surgery recovery, or respiratory illness. It doesn’t measure hydration status or blood pressure, which require separate assessments. Be mindful that readings can be affected by poor perfusion, movement, nail polish, or ambient light, so interpret the data in the broader clinical context.