Predictive Value Of Muscle Tone And Perfusion Index In Supraclavicular Block Success.

Prospective observational pilot study conducted at "Dr. Ignacio Morones Prieto" Central Hospital, Mexico, involving 33 patients (ASA 1, 2, 3) requiring surgery on the distal third of the upper limb with ultrasound-guided SCPB. The motor block was assessed with a conductive ink flexion sensor, and the sympathetic block was evaluated with perfusion index via pulse oximeter at 3, 5, 10, and 15 minutes. Block success was defined as a Numerical Rating Scale (NRS) for pain \<2 during surgical stimulation. Statistical comparisons were made between successful and unsuccessful blocks, with ROC curve analysis identifying optimal cutoff points for predictive variables.