Deep hypothermic circulatory arrest is not a risk factor for acute kidney injury in thoracic aortic surgery

Previous studies describe a high incidence of acute kidney injury after open thoracic aortic surgery. Findings may be confounded by patient selection, including surgery with deep hypothermic circulatory arrest only or emergency procedures. We studied incidence and risk factors of acute kidney injury in patients undergoing thoracic aortic surgery.

We reviewed 851 patients undergoing elective thoracic aortic surgery with and without deep hypothermic circulatory arrest between 2000 and 2007, focusing on clinical outcome and acute kidney injury defined by consensus RIFLE (Risk, Injury, Failure, Loss of function, End-stage renal disease) criteria.

Mean age was 59±16 years; 29% were women. Surgical procedures included aortic root or ascending aorta in 817 patients (96%), aortic arch in 172 (20%), and descending thoracic aorta in 54 (6%), with 20% reoperative procedures. Deep hypothermic circulatory arrest was used in 238 (28%). Incidence of postoperative acute kidney injury (all RIFLE classes) was 17.7%; 2.1% required renal replacement therapy. Mortality increased with RIFLE class severity of acute kidney injury (P<.001). Independent risk factors for acute kidney injury were increased age, elevated body mass index, hypertension, impaired left ventricular ejection fraction, preoperative anemia, and cardiopulmonary bypass duration. Deep hypothermic circulatory arrest, aprotinin use, and preoperative creatinine level were not independently associated with acute kidney injury.

Thoracic aortic surgery can be performed with low rates of acute kidney injury, comparable to other cardiac surgical procedures. Deep hypothermic circulatory arrest and preoperative serum creatinine are not independent risk factors. RIFLE criteria allow comparison with previous studies and correlate well with patient outcome. Risk estimates for acute kidney injury require multivariable prediction.