The erector spinae plane block (ESPB) is a less invasive, safer, and technically easy alternative procedure to conventional neuraxial anesthetic techniques. In contrast to common neuraxial techniques such as paravertebral and epidural injections, the ESPB targets an interfascial plane which is far from the spinal cord, root, and pleura. First applied to thoracic neuropathic pain, currently ESPB is being applied to postoperative pain control and includes variable clinical situations. In the abdomen and thoracic wall, thoracic ESPB can be applied for pain control after cardiac surgery, video-assisted thoracic surgery, laparoscopic cholecystectomy, and thoracotomy. Recently, favorable postoperative pain control after lumbar spinal or lower limb surgeries has been reported with lumbar ESPB. In addition, ESPB has also been used for chronic pain conditions in the upper and lower extremities. The perfusion index (PI) is a numerical value for the ratio between pulsatile and non-pulsatile blood flow measured by a special pulse oximeter. Although the special probe for PI measurement is relatively more expensive compared with ordinary pulse oximetery probes, its benefit as a marker of peripheral perfusion and as an idex for sympathetic stimulation have increased its use progressively. PI has been used widely for the prediction of success of brachial plexus block or axillary block. Changes of PI ratio value showed an excellent predictive value for the success of block.~There have been no studies demonstrating predictive value of PI in lumbar ESPB ESPB for the relief of low back pain or leg pain due to lumbar disc herniation or stenosis.
The primary endpoint of this study was to identify that Perfusion index (PI) has any predictive value for the treatment outcome of cervical radiculopathy