Intrathecal hydromorphone for postoperative pain management in gastrectomy: a dose-finding and randomized controlled study. - Ding, Lin; Leng, Yu; Liu, Hongxin; Jiang, Xiaojuan; Ma, Jun; Gong, Zhichao; Li, Chengyu; Zhou, Cheng; Li, Qian (Anesthesiology & Perioperative Science, 2026)