N-acetylcysteine to Prevent Renal Failure

• Decrease in glomerular filtration defined by at least 30% compared to preoperative levels . [ Time Frame: Within the first 72 hours postoperatively ] [ Designated as safety issue: Yes ]
  

• Up 50% of preoperative levels of serum creatinine. [ Time Frame: Within the first 72 hours after surgery and cardiovascular morbidity and all-cause mortality at thirty days post-operatively. ] [ Designated as safety issue: Yes ]
  
• Death from any cause. [ Time Frame: Within the first 72 hours after surgery and cardiovascular morbidity and all-cause mortality at thirty days post-operatively. ] [ Designated as safety issue: Yes ]
  
• Need for dialysis [ Time Frame: Within the first 72 hours after surgery and cardiovascular morbidity and all-cause mortality at thirty days post-operatively. ] [ Designated as safety issue: Yes ]
  
• Cardiovascular morbidity. [ Time Frame: Within the first 72 hours after surgery and cardiovascular morbidity and all-cause mortality at thirty days post-operatively. ] [ Designated as safety issue: Yes ]
  
• Increased levels of Cystatin C. [ Time Frame: Within the first 72 hours after surgery and cardiovascular morbidity and all-cause mortality at thirty days post-operatively. ] [ Designated as safety issue: Yes ]
  
• Increased levels of NGAL. [ Time Frame: Within the first 72 hours after surgery and cardiovascular morbidity and all-cause mortality at thirty days post-operatively. ] [ Designated as safety issue: Yes ]
  
• Increased levels of isoprostane. [ Time Frame: Within the first 72 hours after surgery and cardiovascular morbidity and all-cause mortality at thirty days post-operatively. ] [ Designated as safety issue: Yes ]
  

Renal failure is a serious and relatively frequent complication of cardiac surgery was observed, especially in diabetics and those with pre-existing renal dysfunction. Given that oxidative stress is elevated in diabetics and in renal and heart, it is reasonable to speculate on its involvement in the pathophysiology of this complication. It is unknown whether the incidence of postoperative renal failure can be reduced by antioxidants. N-acetylcysteine ​​(NAC) is an antioxidant that prevents nephropathy induced by contrast medium and aminoglycosides and increases intracellular levels of cyclic guanosine monophosphate, acting as a vasodilator and platelet inhibitor.

Based on a knowledge of the pathophysiology of ARF, several interventions have been attempted over the past decades. However, various measures employed successfully in the prevention of experimental ARF did not result in success in clinical practice. Much of this failure is probably due to the difference between the experimental models of ARF that encountered in the clinic. Other factors that should be considered, and that may explain the poor results in clinical trials are: the time of use of the drug, dosage and route of administration, are not always adequate.

From the data in the literature, it remains doubtful whether the protective role of NAC is limited only to contrast nephropathy or whether it could have application in other clinical situations in which oxidative stress and vasoconstriction are determinants of injury, as occurs, for example, in CABG surgeries.

NAC is a drug of low cost and low toxicity, this paper intend to assess its role as prophylaxis of renal dysfunction in the postoperative period of CABG in patients with chronic kidney disease stages 3 and 4 (GFR between 15 and 59 mL/min/1, 73 m2 of body surface).