Evaluation of Pulse Oximeter Perfusion Index as an Indicator of Successful Supraclavicular Brachial Plexus Block in Adult Patients Posted for Elective Upper Limb Surgeries

Abstract

Background: Regional anaesthesia has been a part of perioperative medicine for more than a century. Ultrasound guided supraclavicular brachial plexus block is a common technique of regional anaesthesia. The subjective methods to predict success of a block such as assessment of sensory and motor functions are time consuming and depend on patient co-operation. The objective methods available are either time consuming or dependent on sophisticated equipment. The goal of this study was to determine whether the perfusion index (PI) can be used to predict block success and to provide a cut-off value for ultrasound guided supraclavicular brachial plexus block success.

Method:100 patients belonging to American Society of Anaesthesiologists Physical Status (ASA PS) class I and II scheduled for elective hand, wrist and forearm procedure were selected. Ultrasound guided supraclavicular brachial plexus block was performed using 12ml of 0.5% Bupivacaine + 12ml of 2% Lignocaine with adrenaline and PI recorded from 10 min before injection of local anaesthetic (LA) to the brachial plexus to 30 min following block termination at 5 min intervals in both blocked and contralateral unblocked limb while simultaneously assessing both the limbs for sensory and motor weakness thus block success.

Results: At all-time points the PI and PI ratio was higher in the blocked limb when compared with the unblocked limb. The PI at 10 min showed a sensitivity of 73.3% and specificity of 100% for block success at a value of 7.2 and PI ratio showed a sensitivity of 87.8% and specificity of 100% at a cut-off value of 2.26

Conclusion: The PI provides a valuable tool for evaluation of a successful ultrasound guided supraclavicular brachial plexus block. A PI ratio of >2.26 is a good predictor of block success.