IMAGING

Prophylaxis of Contrast Material-Induced Nephropathy in Patients in Intensive Care: Acetylcysteine, Theophylline, or Both? A Randomized Study
Huber W, Eckel F, Hennig M, Rosenbrock H, Wacker A, Saur D, Sennefelder A, Hennico R, Schenk C, Meining A, Schmelz R, Fritsch R, Weiss W, Hamar P, Heemann U, Schmid RM
II. Medizinische Klinik, Institut fur Medizinische Statistik und Epidemiologie, Universitaetsklinik Tuebingen, Kinderkardiologie, Munich, Germany
Radiology. 2006; 239: 793-804

• Purpose: To prospectively compare the protective effect of acetylcysteine, theophylline, and both agents combined in patients who are admitted to the intensive care unit with at least one risk factor for contrast material-induced nephropathy and who receive at least 100 mL of iodinated contrast medium.
• Materials and Methods: Institutional ethics review board approval and informed consent were obtained. A total of 91 patients (mean age, 58.5 years+/-14.8 [standard deviation]; 31 women, 60 men; 150 examinations) were admitted to the intensive care unit with at least one risk factor for contrast-induced nephropathy and received either (a) 200 mg theophylline 30 minutes before contrast medium administration (group T), (b) 600 mg acetylcysteine twice daily on the day of and (if possible) the day before the examination (group A), or (c) both agents combined (group AT). The primary endpoint for this study was the incidence of contrast-induced nephropathy (chi2 test).
• Results: Groups T, A, and AT were comparable with regard to baseline creatinine levels and the amount of contrast medium administered. The incidence of contrast-induced nephropathy in groups T, A, and AT was 2%, 12%, and 4%, respectively, and was significantly lower in group T than in group A (P = 0.047). There was no significant difference in the incidence of contrast-induced nephropathy between groups A and AT (P = 0.148) or between groups T and AT (P = 0.53). For group A, serum creatinine did not change after 12, 24, or 48 hours compared with baseline. Creatinine levels in group T decreased 12 hours (1.19 mg/dL+/-0.58; P = 0.008) and 48 hours (1.16 mg/dL+/-0.55; P = 0.034) after contrast material injection compared with baseline (1.25 mg/dL+/-0.61). In group AT, creatinine significantly decreased 24 hours (1.21 mg/dL+/-0.74; P = 0.003) and 48 hours (1.17 mg/dL+/-0.69; P < 0.001) after contrast material injection compared with baseline (1.28 mg/dL+/-0.74). Group A had significantly higher maximal increases in creatinine than groups T and AT (P = 0.014).
• Conclusion: For prophylaxis of contrast-induced nephropathy in patients who are admitted to the intensive care unit and who receive 100 mL or more of contrast medium, theophylline is superior to acetylcysteine.
  
  
• Editorial Comment
  Although contrast-induced nephropathy is relatively rare in patients with no risk factors, it is considered an import clinical issue since is the third most frequent cause of acute renal failure. The frequency of contrast-induced nephropathy strongly depends on a number of risk factors: pre-existing renal dysfunction (nephropathies associated with diabetes and multiple myeloma), dehydration, congestive heart failure and use of concurrent nephrotoxic medication (including aminoglycosids and amphotericin B). For this reason, several strategies are currently proposed in order to prevent this complication, such as the use of non-contrast based imaging techniques, the reduction of the total amount of contrast material injected, the use of iso-osmolar or low-osmolar contrast agents and hyperhydration. Recently several preventive measures to avoid contrast-induced nephropathy have been proposed which include administration of N-acetylcysteine, theophylline, or fenoldopam, sodium bicarbonate infusion, and peri-procedure hemofiltration/hemodialysis. This is a very interesting and unique prospective randomized study showing that in 150 patients who were admitted to the intensive care unit and who received at least 100 mL of contrast medium, theophylline an “easy to handle” agent was superior to acetylcysteine with regard to prevention of contrast material–induced nephropathy.

Dr. Adilson Prando
Chief, Department of Radiology
Vera Cruz Hospital
Campinas, Sao Paulo, Brazil