ESPB procedures
ESPB
THORACIC
In the operating room, an independent anesthesiologist responsible for the EBPB but not involved in the rest of the protocol performed the procedure. With a patient seated, a 5–12-MHz linear ultrasonic probe (Fujifilm Sonosite Inc., Bothell, WA, USA) was placed parasagittally lateral to the spinous process between Thoracic 10th and 11th level to identify the erector spinae (ES) muscle and the adjacent transverse process. A 22-guage needle was inserted craniocaudally in plane to the transducer through the ES muscle to position the needle-tip near the corresponding transverse process and intertransverse muscles. Thereafter, 2–3 mL of 0.9% saline was injected to determine the appropriate needle position and to detach the ES muscle from the transverse process. Following the confirmation of correct needle position and absence of intravascular puncture, 20 mL of 0.25% bupivacaine at each side (total volume: 40 mL) was injected to the patients in the ESPB group. After the injection, the same procedure was repeated on the contralateral side. For the patients in the control group, an identical procedure, except for the injection of 0.9% normal saline instead of 0.25% bupivacaine, was performed. Because the injected drug was prepared before the intervention without group information, patients and the independent anesthesiologist who performed the ESPB had no knowledge of the group designation.