Discussion
paresthesia, BP block, peripheral block
VASODILATATION, VASODILATION, PARESTHESIA, BLIND
Over the years, several techniques have been used to achieve successful and safe peripheral block application. The paresthesia technique is a blind technique based on direct contact with nerve fibers. This technique is based on the perception of stimulation sensation and is a subjective technique that can be confusing in most cases. The NS technique, on the other hand, is based on finding the inverse relationship between current intensity and distance to show the proximity of the needle to the nerve. The NS technique has been shown to be a highly effective technique for determining the correct needle position for induction of local anesthesia [In our study, after evaluating the vital signs of the patients by monitoring their values, sedoanalgesia was induced with 1 mg midazolam and 50 µg fentanyl before the block procedure. Studies have shown that BP blocks can be performed in awake or mildly sedated patients by an experienced anesthesiologist [Successful BP block is associated with reduced vascular tone and increased blood flow. PI represents the ratio of the pulsatile and non-pulsatile components of peripheral blood flow to each other. During vasodilation, the increase in the pulsatile flow leads to an increase in the PI value. Available data demonstrate that PI is a sensitive parameter to express the vasomotor tone loss induced by LAs. Therefore, PI can be considered an objective measure of peripheral perfusion, which can predict the success of peripheral block [In cases of vasodilatation, a relative increase in the pulsatile blood flow leads to an increase in the PI value. Thus, PI is considered an objective measure for predicting the peripheral block success. The efficacy of PI in predicting the peripheral block success has been demonstrated in BP blocks [Our study aimed to present the diagnostic relationships between sensory block and motor block development and PI values and to determine the optimal cutoff points for PI values. Using the pinprick test, sensory block was detected at 7.98 ± 1.49 min. The mean PI value at which the test became positive was 8.5 ± 2.46. In the ROC analyses, it was seen that an increase of 3.8 units or more in the PI value calculated starting at 5 min after block induction could predict the development of sensory block with 82% sensitivity and 82% specificity. Using MBS grade 3 tests, motor block was detected at 11.08 ± 1.71 min. The mean PI value at which the test became positive was 8.86 ± 2.6. It was found that an increase of 3.9 units or more in the PI value calculated starting at 3 min after block induction could predict the development of motor block on the level of MBS grade 3 with 84% sensitivity and 84% specificity.The literature review revealed that, while there were numerous studies in which PI values demonstrated BP block success, few studies had separately analyzed sensory and motor blocks using PI values. In this sense, our study is the first example of this in the literature. As stated above, the PI cutoff values reported in different studies in the literature differ from each other. It is believed that these differences were caused by differences in the methodologies of the studies, such as the type and volume of LA used, the type of blockades applied, and the experience of the practitioners.Some limitations of our study should be mentioned. Patient-related differences in the assessment of block success may have resulted from the subjective methods we used to evaluate the establishment of the sensory and motor blocks. The fact that the study was single-centered and all infraclavicular blocks were performed by a single anesthesiologist can also be considered as limitation. Finally, PI values vary with age. It is predicted that different age groups have different cutoff values [