Perioperative renal protection: Whom are we treating?

Abstract

Writh an estimated incidence of up to 50% in high-risk vascular procedures, postoperative acute renal failure (ARF) is a complication with potentially disastrous consequences. TM When severe enough to require dialysis, mortality ranges between 64--100%. 124 ICU studies show that patients rarely die of isolated renal failure. Nonetheless, ARF in this setting carries a poor prognosis which has remained largely unaltered over the past 25 years. 5'6 Furthermore, the advent of ARF is associated with an increased length of hospitalization and costs. One recent study of all abdominal aortic surgery patients in Maryland hospitals over a period of 2 years calculated the average cost generated by the complication of post-operative ARF to be $18,414, a 43% increase in hospital costs over those for the patient with an uncomplicated course. 7 When one considers that 67 patients in the study population had this complication, this reflects a total cost of 1.2 million dollars. A further observation was made by Korkeila et al. in a study examining costs generated by renal replacement therapy in ICU patients. Here it was noted that although the average cost per patient was $36,000, the average cost per 6-month survivor was $80,000. 8 In another recent report of a series of 540 thoracic-aortic aneurysm surgeries, postoperative renal failure was a major determinant of prolonged hospitalization .9 ARF is defined as a sudden decrease in glomerular filtration rate (GFR) sufficient to cause (usually) oliguria and the accumulation of normally excreted toxins. Failing the ability to easily measure GFR, clinical proxies are used to diagnose ARF. These include a urine output of <400 mL/