***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: OBJECTIVES Prophylactic acetylcysteine along with hydration seems to be better than hydration alone in preventing the reduction in renal function induced by a contrast dye . BACKGROUND Contrast media can lead to acute renal failure that may occasionally require hemodialysis . METHODS One hundred eighty-three consecutive patients with impairment of renal function , undergoing coronary and /or peripheral angiography and /or angioplasty , were r and omly assigned to receive 0.45 % saline intravenously and acetylcysteine ( 600 mg orally twice daily ; group A , n = 92 ) or 0.45 % saline intravenously alone ( group B , n = 91 ) before and after nonionic , low-osmolality contrast dye administration . RESULTS The baseline serum creatinine concentrations were similar ( 1.5 + /- 0.4 mg/dl in group A vs. 1.5 + /- 0.4 mg/dl in group B ; p = 0.37 ) . An increase of > or = 25 % in the baseline creatinine level 48 h after the procedure occurred in 6 ( 6.5 % ) of 92 patients in group A and in 10 ( 11 % ) of 91 patients in group B ( p = 0.22 ) . In the subgroup with a low ( < 140 ml ) contrast dose , renal function deterioration occurred in 5 ( 8.5 % ) of 60 patients in group B and in 0 of 60 patients in group A ( p = 0.02 ; odds ratio [ OR ] 0.44 , 95 % confidence interval [ CI ] 0.35 to 0.54 ) . In the subgroup with a high contrast dose , no difference was found ( 5/31 vs. 6/32 patients , p = 0.78 ) . By multivariate analysis , the amount of contrast agent , but not the treatment strategy , was a predictor of the occurrence of contrast dye-associated nephrotoxicity ( OR 2.58 , 95 % CI 1.1 to 4.9 ; p = 0.035 ) . CONCLUSIONS In patients with reduced renal function undergoing angiography and /or angioplasty , the amount of contrast agent , but not the administration of prophylactic acetylcysteine , was a predictor of renal function deterioration .  Prophylactic acetylcysteine might provide better protection than hydration alone , only when a small volume of contrast agent is used CONTEXT The antioxidant acetylcysteine prevents acute contrast nephrotoxicity in patients with impaired renal function who undergo computed tomography scanning . However , its role in coronary angiography is unclear . OBJECTIVE To determine whether oral acetylcysteine prevents acute deterioration in renal function in patients with moderate renal insufficiency who undergo elective coronary angiography . DESIGN AND SETTING Prospect i ve , r and omized , double-blind , placebo-controlled trial conducted from May 2000 to December 2001 at the Grantham Hospital at the University of Hong Kong . PARTICIPANTS Two hundred Chinese patients aged mean ( SD ) 68 ( 6.5 ) years with stable moderate renal insufficiency ( creatinine clearance < 60 mL/min [ 1.00 mL/s ] ) who were undergoing elective coronary angiography with or without intervention . INTERVENTION Participants were r and omly assigned to receive oral acetylcysteine(600 mg twice per day ; n = 102 ) or matching placebo tablets ( n = 98 ) on the day before and the day of angiography . All patients received low-osmolality contrast agent . MAIN OUTCOME MEASURES Occurrence of more than a 25 % increase in serum creatinine level within 48 hours after contrast administration ; change in creatinine clearance and serum creatinine level . RESULTS Twelve control patients ( 12 % ) and 4 acetylcysteine patients ( 4 % ) developed a more than 25 % increase in serum creatinine level within 48 hours after contrast administration ( relative risk , 0.32 ; 95 % confidence interval [ CI ] , 0.10 - 0.96 ; P = .03 ) . Serum creatinine was lower in the acetylcysteine group ( 1.22 mg/dL [ 107.8 micromol/L ] ; 95 % CI , 1.11 - 1.33 mg/dL vs 1.38 mg/dL [ 122.9 micromol/L ] ; 95 % CI , 1.27 - 1.49 mg/dL ; P = .006 ) during the first 48 hours after angiography . Acetylcysteine treatment significantly increased creatinine clearance from 44.8 mL/min ( 0.75 mL/s ) ( 95 % CI , 42.7 - 47.6 mL/min ) to 58.9 mL/min ( 0.98 mL/s ) ( 95 % CI , 55.6 - 62.3 mL/min ) 2 days after the contrast administration ( P<.001 ) . The increase was not significant in the control group ( from 42.1 to 44.1 mL/min [ 0.70 to 0.74 mL/s ] ; P = .15 ) . The benefit of acetylcysteine was consistent among various patient subgroups and persistent for at least 7 days . There were no major treatment-related adverse events . CONCLUSION Acetylcysteine protects patients with moderate chronic renal insufficiency from contrast-induced deterioration in renal function after coronary angiographic procedures , with minimal adverse effects and at a low cost Contrast‐induced nephropathy ( CIN ) is a common complication of cardiac catheterization , reported to result in a 15 % incidence of acute renal failure . Convincing evidence supports the prophylactic use of prehydration and low volumes of contrast medium . Recently , the antioxidant acetylcysteine has been shown to have a potential preventive role . The aim of this study was to examine the hypothesis that acetylcysteine prevents CIN . Patients undergoing cardiac catheterization with a serum creatinine ≥ 1.5 mg/dl were prospect ively r and omized to receive acetylcysteine or placebo . A total of five doses of acetylcysteine 600 mg b.i.d . or placebo was administered , commencing on the day of the procedure . All patients were prehydrated with 0.45 % saline and during the catheterization a nonionic low‐osmolality contrast medium was used . Serum creatinine and urea were measured at 24 , 48 , and 72 hr postprocedure . A total of 43 patients were studied . There was no significant difference between the groups in terms of baseline characteristics , including baseline renal function . No adverse events were experienced with acetylcysteine  treatment . Serum creatinine levels at 48 and 72 hr remained largely unchanged in the acetylcysteine group but continued to rise at 48 and 72 hr in the placebo group . By 72 hr , the incidence of CIN , defined as a 25 % increase in baseline creatinine , was significantly lower in the acetylcysteine arm compared to placebo ( 5 % for acetylcysteine vs. 32 % for placebo ; P = 0.046 ) . In patients with mild to moderate renal impairment undergoing cardiac catheterization , prophylactic treatment with oral acetylcysteine  reduces the incidence of contrast‐induced nephropathy . Catheter Cardiovasc Interv 2003;60:458–461 . © 2003 Wiley‐Liss , OBJECTIVES We performed a study to assess the efficacy of fenoldopam mesylate ( a specific agonist of the dopamine-1 receptor ) as compared with N-acetylcysteine ( NAC ) in preventing contrast agent-associated nephrotoxicity ( CAN ) . BACKGROUND Prophylactic administration of NAC , along with hydration , prevents CAN in patients with chronic renal insufficiency who are undergoing contrast media administration . Preliminary data support the hypothesis that fenoldopam might be as effective as NAC . METHODS One hundred ninety-two consecutive patients with chronic renal insufficiency , referred to our institution for coronary and /or peripheral procedures , were assigned r and omly to receive 0.45 % saline intravenously and NAC ( 1,200 mg orally twice daily ; NAC group ; n = 97 ) or fenoldopam ( 0.10 microg/kg/min ; fenoldopam group ; n = 95 ) before and after a nonionic , iso-osmolality contrast dye administration . RESULTS Baseline creatinine levels were similar in the two groups : NAC group = 1.72 mg/dl ( interquartile range , 1.55 to 1.90 mg/dl ) and fenoldopam group = 1.75 mg/dl ( interquartile range , 1.62 to 2.01 mg/dl ) ( p = 0.17 ) . An increase of at least 0.5 mg/dl of the creatinine concentration 48 h after the procedure occurred in 4 of 97 patients ( 4.1 % ) in the NAC group and in 13 of 95 patients ( 13.7 % ) in the fenoldopam group ( p = 0.019 ; odds ratio 0.27 ; 95 % confidence interval 0.08 to 0.85 ) . The amount of contrast media administration was similar in the two groups ( NAC group = 160 + /- 82 ml ; fenoldopam group = 168 + /- 104 ml ; p = 0.54 ) . CONCLUSIONS N-acetylcysteine seems to be more effective than fenoldopam in preventing CAN In recent decades , the management of patients with suspected acute myocardial infa rct ion ( MI ) has progressed substantially through the testing ( and acceptance or rejection ) of a number of different hypotheses . In the 1960s , recognition of the risks of early ventricular fibrillation led to the establishment of coronary care units , emphasis on early hospitalization of patients , and often , the use of prophylactic antiarrhythmic agents ( e.g. , lidocaine).1,2 Various estimates suggest that these approaches were associated with a substantial reduction in early mortality , but the possibility that at least some part of this apparent benefit was due to the hospitalization of lower-risk individuals can not be ruled out . In the 1970s and early 1980s , the concept of myocardial salvage was extensively evaluated by testing drugs with a variety of different mechanisms of action.3 This included early intravenous 83-blockers , hyaluronidase , nitrates , glucose-insulin potassium , calcium blockers , etc.4 Of these agents , the value of intravenous 13-blockers has been confirmed by large r and omized trials5 and that of intravenous nitrates by meta-analyses of several smaller trials.6 However , the use of early intravenous X3-blockers in clinical practice is generally low , and this may relate chiefly to concerns about precipitating heart failure in patients with large MI.7 The late 1980s and early 1990s have seen a shift in focus to various antithrombotic strategies ; of these , the value and efficacy of a thrombolytic agent and aspirin have been demonstrated and are widely accepted.8 The benefit of thrombolytic therapy is greater among patients treated early , with only modest benefits among patients treated within 6 - 12 hours after the onset of symptoms.9 Although the benefits of thrombolytic therapy are considered to be mediated by a reduction in infa rct size and improvement in ventricular function , improvements in ejection fraction have not been dramatic.9 Moreover , some of the adverse effects result in permanent morbidity ( e.g. , reinfa rct ion and strokes ) , and costs of some of these agents are substantial . Although the least expensive thrombolytic agent , streptokinase , is affordable in most Western societies , it still represents a large The aim of this study was to describe the trajectory of creatinine ( Cr ) rise and its determinants after exposure to radiocontrast media . Included were 98 subjects who underwent cardiac catheterization  and were  r and omized  to forced diuresis with i.v . crystalloid , furosemide , mannitol ( if pulmonary capillary wedge pressure was < 20 mmHg ) , and low dose dopamine versus intravenous crystalloid and matching placebos . Baseline and postcatheterization serum Cr levels were analyzed in a longitudinal fashion , allowing for differences in the time between blood draws , to determine the different critical trajectories of serum Cr . The mean age , baseline serum Cr , and Cr clearance ( CrCl ) were 69.3 + /- 10.8 years , 2.5 + /- 0.9 mg/dL , and 31.4 + /- 12.1 mL/min , respectively . The clinical ly driven postprocedural observation time was 5.5 + /- 5.1 days ( range 19 hours and one Cr value to 25.7 days and 18 values ) . The mean maximum Cr was 3.3 + /- 1.4 , range 1.7 - 8.7 mg 
    Output:
    
Conclusion These findings indicate that published studies of acetylcysteine for prevention of contrast-induced nephropathy yield inconsistent results .