Abstract:Objective To investigate the impact of different doses of oxycodone on postoperative levels of pain-causing substances, tissue perfusion, and intestinal barrier in patients undergoing gastrointestinal tumor surgery. Methods Forty-five patients with gastrointestinal tumors who underwent surgery at Lu'an Hospital of Traditional Chinese Medicine from June 2020 to January 2023 were selected and randomly divided into three groups, with 15 in each group. During the anesthesia process, group A received 0.08 mg/kg oxycodone, group B received 0.10 mg/kg oxycodone, and group C received 0.12 mg/kg oxycodone. The blood flow perfusion index (PI) was recorded at anesthesia induction (S1), endotracheal intubation (S2), 30 minutes after the start of surgery (S3), and at the end of surgery (S4). The levels of pain-causing substances ［5-hydroxytryptamine (5-HT) and substance P (SP)］ were detected 1 day before surgery and 2 days after surgery. The intestinal barrier function ［diamine oxidase (DAO), D-lactic acid, and endotoxin (ET)］ was assessed 1 day before surgery and 2 days and 4 days after surgery. Adverse reactions during anesthesia were recorded for the three groups. Results The PI levels of the three groups at S2, S3, and S4 were significantly higher than those at S1, and in group A was higher than in groups B and C (P＜0.05). On 2 days after surgery, the serum levels of 5-HT and SP in three groups were significantly higher than those before surgery, and in group A was higher than in groups B and C (P＜0.05). On 2 days and 4 days after surgery, the serum levels of DAO, D-lactic acid, and ET in three groups were significantly lower than those before surgery, and in group A was lower than in groups B and C (P＜0.05). The overall incidence of adverse reactions during anesthesia in groups A, B, and C (20.00%, 26.67%, 26.67%) showed no statistically significant difference (P＞0.05). Conclusion Compared to 0.08 mg/kg or 0.12 mg/kg oxycodone, anesthesia with 0.10 mg/kg oxycodone can effectively maintain the stability of postoperative pain-causing substances, PI, and intestinal barrier function in patients undergoing gastrointestinal tumor surgery, with good safety.