The Effects of Different Positions on the Diffusion and Blockade Effect of Ultrasound-guided Erector Spinae Plane Block

Eighty-four patients were selected to undergo CT guided puncture localization of pulmonary nodules under local anesthesia, and the patients were divided into groups using a computer-generated random number in a ratio of 1:1:1. To ensure objectivity, a nurse who was not involved in the study prepared a sealed opaque envelope containing grouping information. Randomly divide patients into three groups: supine position group (S group, 28 patients), prone position group (P group, 28 patients), and lateral position group (L group, 28 patients). The patients underwent ultrasound guided ESPB on the puncture side before CT puncture localization. Ultrasound guided ESPB method: Using an ultrasound high-frequency linear array probe (5-13MHz, Sonosite, USA), the probe is placed parallel to the spine on the surface of the transverse process tip of the seventh thoracic vertebrae. Under ultrasound, the transverse process and spinal muscles are clearly exposed. Then, a short inclined plane puncture needle is used, and the needle is inserted from the head side using in-plane technology. After the needle tip reaches between the transverse process and erector spinae muscles, 1ml of physiological saline is injected using water separation technology to confirm the position of the needle tip, Then inject 30ml of local anesthetic solution (0.75% ropivacaine 15ml+iohexol 15ml). After the block was completed, patients in Group S remained in a supine position; Patients in group L maintained the blocking side above; Patients in Group P maintained a prone position. After 30 minutes of block completion, CT scan and puncture localization were performed, following with 3D reconstruction. The primary outcome was LA-contrast spread to the paravertebral space.The second outcomes were as follow: 1. spread to the neural foramina 2. cranio-caudal spread 3. spread to the epidural space 4. spread to the intercostal space.