What is a likely cause for an erratic pulse oximetry signal?

An erratic pulse oximetry signal is likely caused by poor perfusion. Pulse oximeters operate by shining light through a portion of the body, usually a fingertip or earlobe, and measuring the amount of light absorbed by oxygenated and deoxygenated hemoglobin. When perfusion is poor, the blood flow to the area being monitored is insufficient, leading to unreliable readings. This condition can result from various factors such as low blood pressure, hypothermia, or peripheral vascular disease. The inadequate blood flow affects the sensor's ability to obtain a stable and consistent signal, which is why the readings can appear erratic or fluctuating.

Other options, such as excessive calibration, would not typically cause an erratic signal; instead, calibration is meant to ensure accuracy. Proper hemodynamics usually indicate stable blood flow, which would contribute to a reliable signal. Correct positioning of the sensor is also crucial for getting an accurate reading, and if positioned correctly, it should aid in delivering a stable signal rather than leading to erratic results.