Effect of dexamethasone on perioperative renal function impairment during cardiac surgery with cardiopulmonary bypass

Background. In cardiac surgery with cardiopulmonary bypass (CPB),corticosteroids are administered to attenuate the physiologicalchanges caused by the systemic inflammatory response. The effectsof corticosteroids on CPB-associated renal damage have not beendocumented. The purpose of this study was to evaluate the effectsof dexamethasone on perioperative renal dysfunction in patientsundergoing cardiac surgery with CPB. Methods. Renal damage was prospectively studied in 20 patientswithout concomitant morbidity undergoing coronary artery surgerywith CPB. Patients were randomized in a double-blind fashionto receive dexamethasone or placebo. Markers of glomerular function(creatinine clearance) and damage (microalbuminuria), and markersof tubular function (fractional excretion of sodium and freewater clearance) and damage (N-acetyl-ß-D glucosaminidase(NAG)) were evaluated in addition to plasma and urinary glucoselevels. Plasma and urinary specimens were obtained at the followingtime periods: (1) baseline, during the 12 h before surgery;(2) skin incision before heparinization; (3) from heparinizationuntil the end of CPB; (4) during the 2 h following weaning fromCPB; (5) in the intensive care unit from 2 to 6 h after weaningof CBP; (6) and from 36 to 60 h after weaning of CPB. Results. CPB was associated with an increase in markers in theplacebo group, which returned to baseline during the secondpostoperative day, demonstrating a transient impairment of glomerularand tubular renal function. Similar patterns were observed inpatients treated with dexamethasone. While postoperative glycosuriawas significantly higher in the dexamethasone-treated group,no other differences between groups were observed. Conclusion. Dexamethasone administration before CPB has no protectiveeffect on perioperative renal dysfunction in low-risk cardiacsurgical patients.