Renal protective effects of dexmedetomidine in patients undergoing cardiac surgery using cardiopulmonary bypass

Abstract

Background Cardiac surgery-associated acute kidney injury (CSA-AKI) is a serious complication that increases morbidity and mortality rates. Early detection and prevention of this complication is very important. A novel biomarker, neutrophil gelatinase-associated lipocalin (NGAL), can play an important role in the early diagnosis of acute kidney injury (AKI). Recent studies on the favourable effects of dexmedetomidine (DEX) on renal functions have been published. Objective To evaluate the potential protective effects of DEX against the occurrence of AKI, in patients undergoing cardiac surgeries using cardiopulmonary bypass (CPB), whether coronary artery bypass grafting or valvular surgery, regarding urine output (UOP), serum creatinine, creatinine clearance, and urinary NGAL. Patients and methods A prospective randomized double-blind study was conducted, in which 60 adult patients of both sexes, with Cleveland Clinic Score of 0–5, scheduled for elective cardiac surgeries were included. Patients were randomly allocated into two groups: DEX group, where patients received 0.4 µg/kg/h infusion after weaning from CPB, and placebo group (non-DEX) group, where patients received normal saline in the same volume (ml) and rate (ml/h). The primary end point was the incidence of AKI defined by the AKIN criteria of serum creatinine. Urinary NGAL was assessed immediately after anaesthetic induction, and 4 and 24 h postoperatively. Blood urea, serum creatinine, and creatinine clearance were measured just before anaesthetic induction, and every 12 h for 3 days postoperatively. Moreover, UOP was measured intraoperatively and every 4 h for 72 h after surgery. Postoperative pain was assessed using the visual analogue scale every 4 h for the first postoperative day. Results The severity of AKI in DEX group was confined to stage ‘1’, except for one patient, whereas in non-DEX group, five patients developed stage ‘2’, with a significant higher incidence than in DEX group. Urinary NGAL was significantly lower in DEX group, in addition to the significantly higher values in UOP during the postoperative period. Other conventional renal function tests showed comparable results between both groups. A shorter time to extubation and a lower visual analogue scale pain score were accompanying the use of DEX. Conclusion DEX proved to be effective in the prophylaxis against AKI in this cohort of relatively low-risk elective cardiac patients in terms of NGAL values, but did not affect conventional renal functions in terms of serum creatinine, and creatinine clearance, and it was associated with an increase in urinary output. DEX also helped in earlier extubation, and shorter duration of mechanical ventilation. In addition, DEX proved to have potent analgesic properties.