Bilateral erector spinae plane block on opioid-sparing effect in upper abdominal surgery: study protocol for a bi-center prospective randomized controlled trial.

Background: Erector spinae plane block (ESPB) is a promising technique for effective analgesia. It is still uncertain if ESPB offers the same opioid-sparing effect as thoracic paravertebral block (PVB) in midline incision for upper abdominal surgery.

Methods: The study is a prospective, bi-center, randomized, controlled, non-inferior trial.