What parts of the body can you do a pulse oximetry on a patient?

• A. Forehead and nose
• B. Wrist and ankle
• C. Finger tip, ears, toes
• D. Chest and back

Answer: (C)

Pulse oximetry measures oxygen saturation by shining light through tissue and detecting how much is absorbed by pulsatile arterial blood. For a reliable reading, you want a site with good blood flow and minimal interference from movement or nail polish, edema, or poor perfusion. The best places for this are the fingertip, the earlobe, and the toes. These peripheral sites have strong, accessible blood flow and are easy to position a sensor on, which is why they’re commonly used in practice. The fingertip is the most familiar, giving quick, stable readings; the earlobe is handy if the hands aren’t usable (cold hands, injury, or nail polish); and the toes can be used especially in infants or when other sites aren’t available.

Forehead sensors exist on some devices, but they aren’t as universally reliable as the fingertip, earlobe, or toe readings. The nose isn’t a standard site due to less consistent signal and practical issues. The chest and back don’t provide reliable readings for standard pulse oximetry because these areas often have less favorable perfusion and signal quality.

So the valid sites for routine pulse oximetry are the fingertip, ears, and toes.