Intraoperative Dexmedetomidine Enhances Postoperative Microcirculation and Reduces Acute Kidney Injury in Cardiac Surgery: A Double-Blind Randomized Trial.

Purpose: Dexmedetomidine, an alpha-2 adrenergic agonist, has shown potential benefits in various surgical settings, but its impact on microcirculation and renal function in cardiac surgery patients remains unclear. Patients and Methods: This randomized, controlled, double-blind clinical trial was conducted at a single university hospital. Seventy patients undergoing non-emergency cardiac and aortic surgery requiring cardiopulmonary bypass were enrolled, and 68 patients were included in the final analysis. Patients were randomized to receive either dexmedetomidine (0.5 mcg/kg loading dose, followed by 0.5 mcg/kg/h) or saline. The infusion of dexmedetomidine or saline began at anesthesia induction and continued until the end of surgery. Key microcirculatory variables-total vessel density, proportion of perfused vessels, perfused vessel density, De Backer's score, microvascular flow index, and heterogeneity index-were measured at five time points: baseline, 1 hour after cardiopulmonary bypass, 1 hour after arrival in the intensive care unit, 24 hours after surgery, and 48 hours after surgery. Data were analyzed using a mixed-effects model with Tukey's Honestly Significant Difference correction. Intraoperative urine output, the incidence of postoperative acute kidney injury, and other postoperative complications were also compared. Results: Patients in the dexmedetomidine group maintained higher postoperative proportion of perfused vessels and perfused vessel density compared to the saline group, with a significant interaction effect for perfused vessel density. Baseline perfused vessel density was comparable between the two study groups (17.5 [15.9-18.6] vs 18.0 [16.1-19.8] mm/mm², p = 0.540). At 48 hours postoperatively, patients in the dexmedetomidine group had significantly higher PVD values than those in the saline group (17.0 [15.0-19.0] vs 15.6 [13.7-16.9] mm/mm²; P = 0.041). The dexmedetomidine group also had significantly higher intraoperative urine output (950 vs 605 mL, p = 0.002). Additionally, the incidence of postoperative acute kidney injury was significantly lower in the dexmedetomidine group (11.8% vs 50%, p = 0.001). Conclusion: Intraoperative dexmedetomidine infusion during cardiac surgery is associated with higher postoperative microcirculatory state and a reduced incidence of acute kidney injury.