This is a randomized, assessor-blinded, non-inferiority clinical trial comparing continuous thoracic paravertebral block (BPV) versus continuous thoracic epidural block (BPD) for postoperative pain control in adult patients undergoing elective open thoracotomy with one-lung ventilation. The primary outcome is the mean pain intensity at rest assessed by the Numeric Verbal Scale (NVS 0-10) during the first 48 hours after surgery. A total of 80 participants will be randomized 1:1 at Hospital de Clínicas de Porto Alegre, Brazil. The study aims to determine whether BPV provides non-inferior analgesia compared to BPD, with a potential advantage of less hemodynamic interference and better postoperative mobilization.