Which factor could cause a falsely low SpO2 reading aside from the patient’s actual oxygen level?

• A. Position of the sensor could be off
• B. The patient is breathing normally
• C. The device is brand new
• D. The room is quiet

Answer: (A)

The reading can be falsely low when the sensor isn’t positioned correctly. SpO2 devices rely on light shining through a fingertip or earlobe and being detected accurately; if the sensor isn’t seated snugly, is misaligned, or isn’t contacting the skin well, the signal quality drops and the device can underestimate the oxygen saturation even if the blood’s oxygen level is normal. Movement, loose fit, or placing the sensor on a site with poor perfusion can all produce that falsely low result.

Breathing normally doesn’t by itself cause a falsely low SpO2 reading; a brand-new device doesn’t inherently lower the reading, and the room’s noise level doesn’t affect the measurement. The key factor here is the sensor’s position and contact.