In addition to the finger, what is an alternate location for performing a pulse oximetry?

• A. Earlobe
• B. Chest
• C. Toe
• D. Forehead

Answer: (C)

Pulse oximetry works by detecting pulsatile arterial blood to estimate oxygen saturation, so any site with good blood flow and manageable tissue thickness can be used, not just the finger. The toe is a common alternate peripheral site because it has arterial pulsations similar to the finger and remains accessible when hands aren’t convenient or when a patient’s hands are unavailable or restricting sensors. Using the toe allows continuous monitoring in situations where finger probes won’t fit or reliable signal is hard to obtain from the digits. However, readings from the toe can be influenced by peripheral perfusion, temperature, or movement, and may respond a bit more slowly than finger readings. Chest isn’t a typical site because it doesn’t reliably provide the pulsatile signal needed for noninvasive SpO2 measurement, and the forehead or earlobe can be used when hands aren’t ideal, but the toe remains a valid alternative in many clinical scenarios.