Which site besides the finger is commonly used for pulse oximetry?

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

Answer: (C)

Pulse oximetry relies on detecting a pulsatile arterial signal, and while the finger is the usual site, other accessible digits can provide reliable readings when the hands aren’t usable. The toe is a practical alternative because it has a similar arterial supply and is often accessible without interfering with the upper limbs. It’s commonly used in neonates and small children, or when the hand or wrist is injured, immobilized, or edematous, making finger placement impractical. For best results, keep the toe warm, ensure the sensor fits properly, and avoid nail polish or thick coverings that can block light. Be aware that readings can be influenced by peripheral perfusion, temperature, and motion, just as with the finger.