Which noninvasive device is used to estimate arterial oxygen saturation and pulse rate in flight medicine?

• A. Capnograph
• B. Pulse oximeter
• C. ECG monitor
• D. Blood gas analyzer

Answer: (B)

Estimating arterial oxygen saturation and pulse rate noninvasively in flight medicine is done with a pulse oximeter. This device sits on a fingertip or earlobe and uses two light wavelengths to assess how much oxygenated versus deoxygenated hemoglobin is present in the blood. By measuring the absorption of red and infrared light, it derives an SpO2 value (arterial oxygen saturation) and, from the pulsatile signal, a pulse rate. It’s quick, portable, and safe for in-flight use, making it ideal for routine checks and continuous monitoring.

The other options don’t fit this purpose as well. A capnograph monitors CO2 levels to assess ventilation status, not oxygen saturation. An ECG monitor records the heart’s electrical activity and rhythm, providing heart rate, but not SpO2. A blood gas analyzer requires blood sampling and laboratory equipment to measure gases and pH, so it’s invasive and not suitable for noninvasive in-flight monitoring.

Be aware of limitations: accuracy can be affected by motion, poor peripheral perfusion, cold fingers, nail polish, or certain abnormal hemoglobins, but when used properly it provides a reliable, noninvasive readout of oxygenation and heart rate.