Background and Goal of Study: Dexmedetomidine (DEX), an alpha-2 selective agonist, alleviates reperfusion injury in both experimental and clinical studies.  However, its effects during one-lung ventilation (OLV) remain unclear. 
Materials and Methods: After obtaining approval from an institutional ethics board and consent from each patient, 60 adult patients undergoing video-assisted thoracoscopic surgery (VATS) were randomly divided into two equal groups—DEX (receiving 0.5 µg/kg/h DEX infusion throughout surgery; N = 30) and control (receiving saline infusion; N = 30). OLV was performed using a double-lumen tracheal tube or bronchial blocker. During surgery, the patients in both groups underwent treatment protocols with the same ventilator settings (tidal volume: 8 mL/kg for two-lung ventilation and 5 mL/kg for OLV) and haemodynamic control. Serum levels of proinflammatory biomarkers, including high mobility group box 1 protein (HMGB1), interleukin-6 (IL-6), and monocyte chemoattractant protein-1 (MCP-1), were measured and compared between the two groups at the baseline (T1), 1 h after resumption of two-lung ventilation from OLV (T2), and postoperative day 1 (T3).
Results and Discussion: The patients in both groups exhibited similar intraoperative profiles. The DEX group patients tended to have a lower incidence (16.7% vs. 33.3%, p = 0.2326) and shorter length (0.2 ± 0.6 vs. 0.8 ± 1.7 day, p = 0.1152) of intensive care unit stay. Attenuated serum inflammatory responses were observed among the DEX group patients: (1) The DEX group exhibited a significant decrease in HMGB1 levels between T1 and T2 (51.7 ± 58.1 and 33.9 ± 45.0 ng/mL, respectively; p = 0.0051). (2) The DEX group had lower IL-6 levels at T3 (DEX vs. control: 78.5 ± 58.5 vs. 118.8 ± 68.8 pg/mL; p = 0.0255). (3) MCP-1 levels increased between T1 and T2 in the control group (151.8 ± 130.4 and 235.2 ± 135.9 pg/mL, respectively; p = 0.0427) but not in the DEX group. HMGB1 is present in the nuclei of the majority of mammalian cells; on its release in serum, HMGB1 acts as a damage-associated molecular pattern molecule and initiates potent innate immune responses by upregulating the expression of cytokines, including IL-6 and MCP-1. These inflammatory responses are strongly associated with lung injury development. Thus, DEX infusion has protective effects during OLV in thoracoscopic surgery.
Conclusion: DEX infusion during VATS effectively alleviates OLV-induced inflammatory responses.

Effects of dexmedetomidine infusion on inflammatory responses during one-lung ventilation in thoracoscopic surgery: a randomised controlled trial