A propensity score-matched comparison of deep versus mild hypothermia during thoracoabdominal aortic surgery

Objective: By using deep hypothermic circulatory arrest and non-deep hypothermic circulatory arrest approaches, we examined the impact of distal ischemia time and temperature on intra-abdominal reversible adverse outcomes and permanent adverse outcomes during descending thoracic aortic and thoracoabdominal aortic aneurysm operations.

Methods: A retrospective review of all patients who underwent descending thoracic aortic and thoracoabdominal aortic aneurysm repair between January 2002 and December 2008 was undertaken, including relevant preoperative, intraoperative, and postoperative data, and followed by a propensity score-matched analysis. Of the total of 262 patients, 240 had data complete enough to permit analysis, and 90 were suitable for the propensity-matched study. Reversible adverse outcomes included renal failure, liver failure, and temporary hemodialysis. Permanent adverse outcomes included paraplegia, permanent hemodialysis, and 30-day mortality.

Results: Thirty-day mortality was 7.1% (17/240). Overall, reversible adverse outcomes developed in 40.8% of patients and permanent adverse outcomes developed in 10% of patients. The propensity score analysis identified statistically significant decreased odds of developing reversible adverse outcomes in patients undergoing deep hypothermic circulatory arrest (odds ratio, 0.32; confidence interval, 0.12-0.85). Specifically, significantly lower rates of acute renal failure (22% vs 46.4%, P = .03) and liver failure (17.8% vs 34.3%, P = .04) were observed in the deep hypothermic circulatory arrest group compared with the non-deep hypothermic circulatory arrest group. In addition, there were decreased odds of reversible adverse outcomes (odds ratio, 0.22; confidence interval, 0.06-0.79) developing in patients with a stage II elephant trunk procedure.

Conclusions: During descending thoracic aortic and thoracoabdominal aortic aneurysm repairs, the use of deep hypothermic circulatory arrest results in improved postoperative adverse outcome rates compared with non-deep hypothermic circulatory arrest techniques. The development of reversible adverse outcomes is strongly associated with the development of permanent adverse outcomes.