Perfusion Index Value in Determining the Success of Block

Objective: To evaluate whether the perfusion index (PI) can be used to predict and provide a cut-off value for ultrasound-guided axillary nerve block success. Study Design: Quasi-experimental study. Place and Duration of Study: Department of Anaesthesiology and Reanimation, Adiyaman University Training and Research Hospital, Adiyaman, Turkey, from July to August 2020. Methodology: Fifty patients between the ages of 18 and 65 years, who were in the ASA 1-2 group, undergoing hand, wrist and forearm surgery, were included in the study. PI value was measured from the extremity to the block and the healthy extremity before and after the procedure. Sensory block was evaluated with the pin-prick test, Motor block was evaluated with the Modified Bromage Scale. The minutes when sensory and motor blocks occurred were recorded, and the PI value at these moments were recorded. Results: Pin-prick test was positive in patients at average 8.4 +/- 2.4 minutes. The average PI value for which the pin-prick test was positive was 7.41 +/- 2.54, and the cut-off value of the sensory block PI ratio was determined as 1.7 times. The modified Bromage scale reached a score of 2 in 7.6 +/- 2.3 minutes on average. The average PI value is 7.27 +/- 2.69 for which the modified Bromage Scale score is 2. At modified Bromage Scale-2, PI ratio cut-off value was determined as 1.7 times. The modified Bromage Scale reached a score of 3 in an average of 12.6 +/- 4.2 minutes. The mean PI value for the modified Bromage Scale score of 3 is 9.56 +/- 6.97. The motor block PI ratio cut-off value was determined as 1.9 times. Conclusion: Pulse oximetry perfusion index is a sensitive and simple method that can be used to evaluate the success of axillary block. The cut-off value, indicating successful block for the rate of sensory block and modified Bromage scale PI, was determined as 1.7 times and the motor block PI ratio as 1.9 times.