Pain management after open abdominal surgery still faces severe challenges, with the incidence of moderate to severe pain after surgery as high as 50 - 90%. Insufficient analgesia can hinder early mobilization of patients, delay gastrointestinal function recovery, increase the risk of complications, thereby reducing the quality of patient recovery and prolonging hospital stay.
The Enhanced Recovery after Surgery (ERAS) pathway has significantly improved surgical outcomes. Multimodal analgesia based on transversus abdominis plane block (TAPB) analgesia is the core of ERAS for abdominal surgery. However, the existing multimodal analgesia regimens still inade-quately control visceral pain, resulting in the failure to significantly reduce the dosage of opioid drugs, which has become a key bottleneck restricting the smooth recovery of patients.
Intrathecal morphine (ITM) directly delivers the drug to the dorsal horn of the spinal cord through cerebrospinal fluid, providing potent and long-lasting visceral analgesia. Although its analgesic effect is clear, in the context of modern ERAS with routine application of TAPB, there is still insufficient evidence regarding the impact of ITM on the quality of recovery - a multi-dimensional core outcome - in patients undergoing open abdominal surgery. In addition, whether its effect is affected by key factors such as age (e.g., \>60 years) or surgical site (upper abdomen vs. lower abdomen) also remains to be clarified.
Therefore, in this prospective, multicenter, randomized, double-blind, placebo-controlled trial, we aimed to evaluate whether single-dose preoperative ITM can further improve the quality of recovery in the ERAS pathway based on TAPB and to verify the efficacy differences of ITM in important subgroups.