Renoprotective Effects of Dexmedetomidine Preconditioning in CABG Surgery

Acute kidney injury (AKI) is one of the most frequent complications of coronary artery bypass graft (CABG) surgery performed with cardiopulmonary bypass (CPB). Even small postoperative rises in serum creatinine are associated with longer intensive care stay and higher mortality. Ischemia-reperfusion injury, the systemic inflammatory response elicited by contact of blood with the bypass circuit, and heightened perioperative sympathetic activity are believed to contribute to its development. Dexmedetomidine is a selective alpha-2 adrenergic receptor agonist used as a sedative and anesthetic adjunct. It attenuates sympathetic outflow and has shown anti-inflammatory and organ-protective properties in experimental models and in some cardiac surgical populations, but whether it reduces AKI after on-pump CABG surgery has not been established. This is a prospective, randomized, double-blind, placebo-controlled, single-center trial in adults undergoing elective CABG surgery with CPB. One hundred patients aged 18-80 years, ASA physical status II or III, with a preoperative serum creatinine below 1.5 mg/dL are allocated 1:1 to a dexmedetomidine group (n=50) or a control group (n=50). Patients in the dexmedetomidine group receive a loading dose of 1 microgram/kg over 15 minutes after central venous catheterization, followed by a maintenance infusion of 0.5 microgram/kg/h until the start of CPB. Patients in the control group receive an equal volume of 0.9% sodium chloride over the same period and with the same infusion scheme. In both groups the infusion is stopped when CPB begins; no study drug is given during bypass or postoperatively. Anesthesia, surgery, CPB conduct, fluid and vasoactive therapy, and postoperative intensive care follow a standardized protocol with identical numerical thresholds in both groups, applied by clinicians unaware of group allocation. The primary outcome is the incidence of postoperative AKI within the first 72 hours, staged according to the seru