Prevention of contrast-induced nephropathy by N-acetylcysteine in critically ill patients: Different definitions, different results

Abstract

PurposeThe use of N-acetylcysteine (NAC) for preventing contrast induced nephropathy (CIN) is debated in the intensive care unit. NAC may alter the concentration of serum creatinine and interfere with CIN diagnosis. The effectiveness of NAC was evaluated with a special attention on its specific effect on creatinine levels compared to cystatin C. MethodsIn a first period, we prospectively enrolled patients receiving saline and low osmolality contrast media for 140 exams in 2 intensive care units with opposite policies regarding the use of NAC. Renal impairment was defined by both the classical CIN and the “sensitive” Acute Kidney Injury Network (AKIN) (taking creatinine and diuresis) definitions. In a second period, we compared the evolution of serum creatinine and cystatin C after 23 additional contrast examinations under NAC. ResultsSeventy exams with and without NAC were compared in the first period. Risk factors for CIN were similar in the two intensive care unit populations. No difference in CIN incidence was found with and without NAC, using the CIN (10/70 vs 15/70) or the AKIN (24/70 vs 22/70) definition. Interestingly, NAC seemed to reduce renal impairment when the creatinine criterion of the AKIN definition was considered alone [9% vs 21%, P = .033]. Overall, the incidence of renal impairment was 18%, 33% and 15% using the CIN definition, the AKIN, or using AKIN with creatinine alone. Serum creatinine significantly decreased after exams with NAC while cystatin C remained stable. ConclusionThe incidence of CIN does not seem to be influenced by NAC, except if small changes in creatinine only are considered.