RESUMO
BACKGROUND: Acute renal failure (ARF) occurring after on-pump and off-pump cardiac surgery was assessed by urinary alpha glutathione S-transferase measurement (alpha-GST) in patients who already had renal dysfunction. METHODS: Fifty-one patients with plasma creatinine levels ranging between 1.5 and 2.0 mg/dL were included in the study. On-pump coronary artery bypass was performed in 25 of them, and off-pump surgery in the other 25 patients. Urinary alpha-GST levels, plasma creatinine levels, creatinine clearance and fractional excretion of sodium were measured. RESULTS: Urinary alpha-GST levels were found to be significantly increased at 24 hours postoperatively. A weak correlation was detected between alpha-GST levels and plasma creatinine, creatinine clearance and fractional excretion of sodium. Preoperative and postoperative 24 hour levels showed a positive predictive value for the occurrence of acute renal failure. CONCLUSIONS: Tubular damage produced by cardiopulmonary bypass is not the only factor associated with postoperative ARF. Because factors independent of pump usage can adversely affect renal function, excluding pump usage alone is not sufficient to prevent postoperative ARF in patients who have preoperative renal dysfunction.