Which statement best describes SpO2 measurement?

• A. Heart Rate
• B. Oxygen Saturation of Blood
• C. Blood Glucose
• D. Respiratory Rate

Answer: (B)

SpO2 measurement tells you the percentage of hemoglobin in arterial blood that is carrying oxygen. A pulse oximeter estimates this by using light to distinguish oxygenated from deoxygenated hemoglobin, then reports a percent that reflects how saturated the blood is with oxygen. Normal values are typically about 95–100%. This reading isn’t a measure of heart rate, blood glucose, or respiratory rate, but of how well oxygen is being carried by the blood to tissues. Several factors can affect accuracy, such as poor circulation, motion, cold fingers, nail polish, or conditions like carbon monoxide poisoning or methemoglobinemia. It’s also different from arterial oxygen tension (PaO2), which requires blood gas analysis.