[Effect of gamma-hydroxybutyric acid and pentoxifylline on kidney function parameters in coronary surgery interventions].

After cardiac surgery, transient renal dysfunction often occurs. The main reasons for impairment of renal function are intraoperative hypotension, ischemia/reperfusion injury and inflammatory response to cardiopulmonary bypass (CPB). Pentoxifylline is known to have anti-inflammatory properties. Gamma-hydroxybutyrate (GHB), an endogenous regulator of energy metabolism, showed beneficial effects on experimental intestinal ischemia/reperfusion injury and liver graft function. Both drugs may be of practical interest in diminishing renal damage during and after cardiac surgery. After approval by the ethics committee and informed consent, 45 patients for elective coronary artery bypass grafting with no clinical and laboratory impairment of renal function were randomized into 3 groups (15 patients each): group 1 received saline as control, group 2 received pentoxifylline intraoperatively (1 mg/kg/h after a priming dose of 1 mg/kg) and group 3 received GHB intraoperatively (25 mg/kg/h after a priming dose of 25 mg/kg) in a double-blinded fashion. During 3 periods (before CPB, from the beginning of CPB until the end of surgery, 24 hours postoperatively), glomerular (creatinine clearance, CCr) and tubular markers of renal function (beta-NAG, alpha 1-microglobulin) were detected in addition to clinical routine standards (creatinine, urea, fractional excretion of sodium). Changes in glomerular and in tubular function were comparable in all groups without characteristic effects of either GHB or pentoxifylline. With CPB, CCr decreased significantly until the end of operation, but showed a rise to preoperative levels on the first day after operation. Tubular function markers (beta-NAG, alpha 1-microglobulin, related to simultaneous excretion of creatinine) showed a remarkable rise after the beginning of CPB up to the postoperative period. The results of the present pilot study suggest the detection of tubular proteins and enzymes a useful addition to present routine clinical standards for recognizing early intraoperative changes in renal function. In the patients studied, there were no clinical signs of renal dysfunction. Neither GHB nor pentoxifylline--in the doses applied--was able to show a therapeutic benefit despite the theoretical advantages.