Pulse oximeter waveforms from the finger and toe during lumbar epidural anesthesia

Abstract

Background and objectives: To determine whether lumbar epidural anesthesia affects pulse oximeter signals in the upper or lower extremity, 13 ASA I patients were studied.

Methods: Temperature and pulse oximeter probes were placed on the finger and the toe.

Results: After epidural injection, the amplitude of the pulse oximeter waveform on the toe increased eight-fold but declined by 50% in the finger. The increase in amplitude of the pulse oximeter waveform in the foot preceded the temperature rise.

Conclusions: More reliable pulse oximeter signals may be obtained from the toe than the finger during lumbar epidural anesthesia. Furthermore, the increase in the pulse amplitude from the toe may aid in the early detection of successful epidural block.