Local Perfusion Failure Caused by the Incorrect Attachment of an SpO₂ Sensor During General Anesthesia

We present a case in which excessive pressure caused local perfusion failure and a decrease in peripheral oxygen saturation (SpO₂) readings in a 10-year-old boy undergoing general anesthesia for a cleft lip and alveolus operation. The pulse oximeter sensor was placed on his left index finger and held in place using adhesive tape before the induction of general anesthesia. Roughly 90 minutes into the operation, his SpO₂ became unstable, decreasing rapidly to 85% and returning to 94% repeatedly. As we suspected a problem with the sensor, it was replaced, and his SpO₂ readings returned to 100%. However, inspection of his index finger revealed dark purple skin near the sensor, indicating constriction of the underlying vessels attributed to excessive pressure from the adhesive tape. Proper sensor placement is crucial for accurate SpO₂ monitoring.