Visceral organ protection in aortic arch surgery: safety of moderate hypothermia

Although antegrade selective cerebral perfusion (ASCP) provides good brain protection during aortic arch surgery, the issue of distal organ protection during circulatory arrest remains to be clarified. The aim of the study was to retrospectively evaluate the outcome of aortic arch surgery using ASCP at different temperatures, focusing on visceral functions (VFs). Three hundred and thirty-four patients underwent elective aortic arch surgery using ASCP from November 1996 to March 2011. Those patients without early postoperative low cardiac output syndrome were included. VFs were evaluated by comparing preoperative and postoperative creatinine, aspartate amino transferase, alanine amino transferase and bilirubin. Univariate and multivariate analysis were performed. Three hundred and four patients represent the cohort of the study. Deeper systemic hypothermia (a parts per thousand currency sign25A degrees C) (Group A) was used in 194 patients (63.8%) and moderate hypothermia (> 25A degrees C) (Group B) in 110 patients (36.2%). The 30-day mortality rate was 3.6% in Group B and 5.2% in Group A (P = NS). Permanent neurological deficits occurred in 4 (3.6%) and in 14 patients (7.2%) of Group A and Group B, respectively (P = NS). Postoperative renal insufficiency requiring dialysis occurred in 6 patients (5.4%) in Group A and in 15 patients (7.7%) in Group B, the differences were not statistically significant. Biochemical markers of VFs increased in the postoperative period without differences between groups. At the multivariate analysis, cardiopulmonary bypass time > 180aEuro integral min (odds ratio (OR) = 2.16) was the only significant risk factor for renal dysfunction with or without liver dysfunction, while cardiopulmonary bypass time longer than 180aEuro integral min (OR = 2.28) and hypothermia higher than 25A degrees C (OR = 0.54) were found to be independently related to liver dysfunction. Our results confirmed that ASCP with moderate hypothermia at 26A degrees C is a safe method for brain protection. Moreover, during circulatory arrest, moderate hypothermia also offers good protection of visceral organs and it should be preferred for limited periods (< 60aEuro integral min) of visceral ischaemia because it may reduce the systemic inflammatory response and the reperfusion organ injury.