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

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.