Usefulness of perfusion index in evaluation of stellate ganglion block

[Abstract] Clinical conditions such as Horner's syndrome and conjunctival injection have conventionally been used post-treatment to evaluate stellate ganglion block (SGB). Recently, there have been occasional reports of using a perfusion index (PI) obtained using a pulse oximeter to evaluate improved peripheral blood flow. In this study, we investigated whether the PI value from the blocked side is useful in evaluating the effects of SGB following treatment. A pulse oximeter sensor was placed on the fingertip of a patient diagnosed with glossalgia, and after measuring the PI value to use as the control value, SGB was performed 10 times. PI values before and after the procedure were compared, and while the PI value fell significantly immediately following the procedure, it then rose significantly between 2 and 20 minutes after treatment, peaking at about the 5-minute mark. In the post-SGB evaluation, conditions such as Horner's syndrome and conjunctival injection were acknowledged on the blocked side. SGB blocks the sympathetic nerves and increases the volume of blood flow in the head and neck, face, and extremitas thoracica of the affected side, improving peripheral circulation. Accordingly, the PI value, which is said to correlate with peripheral blood flow, can be considered useful in evaluating the effects of SGB. In this case, the PI value in the fingertips on the blocked side rose following the SGB, peaking at approximately the 5-minute mark, clearly indicating increased peripheral blood flow from the initial phase after the SGB. The PI value was therefore considered useful in evaluating the effects of SGB.