Introduction Colon cancer is a common malignancy, for which surgery is currently the preferred therapy. Aim To assess the effect of transversus abdominis plane block (TAPB) combined with low-dose dexmedetomidine on elderly patients undergoing laparoscopic colectomy. Material and methods Sixty-two elderly patients undergoing laparoscopic colectomy between March 2021 and March 2022 were randomly selected and equally divided into Group A (low-dose dexmedetomidine) and Group B (TAPB + low-dose dexmedetomidine) by the randomized double-blind method. The treatment outcomes were compared. Results The resting and active Visual Analogue Scale and Pittsburgh Sleep Quality Index scores were lower in Group B than those in Group A at 6 h, 1 day, 2 days and 3 days after operation (p < 0.05). The two groups had no significant differences in the levels of cluster of differentiation 4+ (CD4+), CD8+ and free Cor, CD4+/CD8+ ratio and NK cell level before anesthesia (p > 0.05). At 24 h after the operation, the level of CD4+, CD4+/CD8+ ratio and NK cell level were higher in Group B than those in Group A, and the levels of CD8+ and free Cor were lower in Group B (p < 0.05). Group B had higher partial pressure of oxygen ((45.52 ±11.14) mm Hg) and pH (7.42 ±0.06) (p < 0.05) and lower partial pressure of carbon dioxide ((4.05 ±0.32) mm Hg) than those of Group A (p < 0.05). Conclusions TAPB combined with low-dose dexmedetomidine can exert better anesthetic, analgesic and sedative effects, and ameliorate stress responses.

Background: Pain after colon cancer surgery can be effectively relieved by transversus abdominis plane (TAP) block. We aimed to determine the optimal dose of dexmedetomidine for preemptive analgesia when combined with TAP block after colon cancer surgery.Methods: A total of 120 patients undergoing laparoscopic resection for colon cancer from March 2018 to October 2019 were randomly assigned to control (group C), low-dose (group L, 0.5 μg/kg), moderatedose (group M, 1 μg/kg), and high-dose groups (group H, 1.5 μg/kg) (n=30 each). After puncture under ultrasound guidance, the designated dexmedetomidine dose and 0.25% ropivacaine were injected on both sides (20 mL each side). Mean arterial pressure (MAP), heart rate (HR), numeric rating scale (NRS) score, and Ramsay score were compared at 2 h (T0), 4 h (T1), 8 h (T2), 12 h (T3), 24 h (T4), and 48 h (T5) after surgery. The area sensitive to mechanical stimulation-induced pain at the incision was measured at T4, T5, and 72 h after surgery (T6). Adverse reactions were compared.Results: MAP and HR were lower in the dexmedetomidine groups, especially groups M and H, than in group C (P<0.05). NRS scores at T0-T5 and pain-sensitive areas at T4-T6 were lower in the dexmedetomidine groups than in group C (P<0.05), but Ramsay scores were similar (P>0.05). Compared with group L, groups M and H had lower NRS scores and pain-sensitive areas (P<0.05). The incidence rates of adverse reactions were lower in the dexmedetomidine groups than in group C (P<0.05).Conclusions: Dexmedetomidine 1 or 1.5 μg/kg is effective and did not increase adverse reactions. A dose of 1 μg/kg is recommended as an adjuvant to ropivacaine for TAP block.