Pulse Oximeter Perfusion Index as an Early Indicator of Onset of Sympathectomy After Epidural Anaesthesia

Abstract

Objective: To establish a reliable indicator of epidural effectiveness, we compared the frequency of subjects achieving sympathectomy onset in patients undergoing lower limb surgeries under lumbar epidural anaesthesia in terms of changes in perfusion index (PI), mean arterial pressures (MAP), and toe temperature.

Methodology:  This descriptive case series study was conducted at the Department of Anesthesiology, Holy Family Hospital, Rawalpindi from July 2018 - January 2019. A total of 96 patients were included, all of them received lumbar epidural catheters for lower limb surgeries and were given 10 ml of epidural bupivacaine 0.5% through the epidural catheter. Baseline values were recorded for PI in toe, MAP and temperature of toe. At 5, 10 and 20 minutes after epidural anaesthesia, these values were re-recorded. Data collection was completed before the start of surgery. Criteria for clinically evident sympathectomy was defined beforehand. The frequency of subjects reaching these predefined targets were analyzed at said time intervals using Mc-Nemar test at each time interval.

Results: For PI 66/96, 88/96 and 96/96 of subjects in the study fulfilled the criteria of achieving sympathectomy at 5, 10 and 20 minutes , respectively, compared to 7/96 , 15/96 and 59/96 for MAP changes and 0/96, 29/96 and 45/96 for changes in temperature of toe.

Conclusion: As per this study, PI seemed to be a faster, clearer and a more objective indicator of the onset of sympathectomy after epidural anaesthesia than toe temperature or MAP.