Background Surgical stress may cause immunosuppression especially in patients who have surgery for primary tumor removed. This study aimed to explore the effects of dexmedetomidine on immune and inflammatory response in patients undergoing radical gastrectomy. Methods After the institutional review board approval and written informed consent, forty patients undergoing radical gastrectomy were equally randomized to receive dexmedetomidine infusion (Dex group; 0.5 μg·kg-1 initial dose followed by a maintenance dose of 0.4 μg·kg-1 h-1) or normal saline infusion (NS group). Helper T lymphocytes (T helper 1 [Th1] and T helper 2 [Th2]), tumor necrosis factor-α, and interleukin-6 were measured during and after surgeries. Plasma catecholamine levels were also measured during surgery. Postoperative pain was measured by a visual analog scale. Results The percentage of Th1 increased significantly at the end of surgery, 24 h after surgery (P = 0.045 and 0.048, respectively), and Th2 decreased notably at the end of surgery in the Dex group (P = 0.030). Plasma levels of tumor necrosis factor-α (P = 0.045 and 0.036, respectively) and interleukin-6 (P = 0.049 and 0.042, respectively) differed significantly at the end of surgery and 24 h after surgery. Plasma epinephrine and norepinephrine levels decreased significantly at the beginning of surgery in the Dex group (P = 0.020 and 0.015, respectively). At the end of surgery, plasma dopamine levels decreased significantly in the Dex group (P = 0.048), but increased in the NS group. The visual analog scale pain score was lower in the Dex group than in the NS group 24 h after surgery (P = 0.046). Conclusions Dexmedetomidine has been shown to reduce surgical stresses and maintain Th1/Th2 balance. It has been shown to reduce inflammatory responses and exerts immunoprotective effect.
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