Investigating the perfusion index CUT-OFF value showing the success of the infraclavicular block made with ultrasound

Objective: Ultrasound-guided infraclavicular block is a frequently used approach for upper extremity procedures. Nowadays, the frequency of studies on the perfusion index (PI), which can be used as a criterion for the evaluation of block success, is increasing. The aim of this study is to evaluate the success and efficiency of infraclavicular approach block with perfusion index using ROC (Receiver Operating Characteristic) curves. Method: In our prospective observational study, a total of 50 patients between the ages of 18 and 65, with ASA (American Society of Anesthesiologists) risk rating I-II, planned for upper extremity surgery, were included. PI was measured non-invasively at the beginning of the block, at the 5th, 10th and 20th minutes by infraclavicular blockage under the guidance of Ultrasonography(USG) and peripheral nerve stimulator. Results: The time to become positive for the pin-prick test was 7.98 ± 1.49 minutes, and the time for Modified Bromage scale (MBS), Stage-2 and 3 to become positive was 6.68 ± 1.97 and 11.08 ± 1.71 min, respectively. When the PI levels were compared in pairs, the difference between basal measurement and the 5th min, 10th min, 15th min, 20th min, 25th min and 30th min was found to be significant. Increases in PI levels of 3.8 units and above were diagnostic for sensory block, increases in PI levels of 3.9 units and above were diagnostic for MBS Stage-3, there was a poor diagnostic accuracy between MBS, Stage-2, and PI levels. Conclusion: We were able to predict the development of sensory and motor block by looking at PI levels. Increases in PI levels of 3.8 units and above were associated with the development of sensory block. Increases in PI levels of 3.9 units and above were associated with development of motor block (Stage-Ⅲ MBS). It was concluded that the perfusion index is a faster, objective and simpler method compared to traditional methods, due to the vasodilation that develops before sensory and motor blockade in evaluating block success Keywords: İnfraclavicular block, perfusion index, roc curve