A 65-year-old man has urine output of 10 mL/h following abdominal aortic aneurysmectomy. Acute tubular necrosis is suggested by the presence of which of the following?
Urine osmolality of more than 500 mOsm/kg Urine sodium of more than 40 mEq/L Fractional excretion of sodium of <1% Blood urea nitrogen (BUN)-to-serum creatinine ratio (SCR) of more than 20