Effect of lower-body ischemia duration in aortic arch surgery under mild-to-moderate hypothermic circulatory arrest

Objectives: Aortic arch surgery is performed at increasingly higher circulatory arrest temperatures. This might affect visceral protection. We analyzed the effect of visceral ischemic time in arch surgery under mild-to-moderate hypothermia. Methods: We divided the population into 3 groups: group 1 (visceral ischemic time ≤30 minutes), group 2 (31-60 minutes), and group 3 (>60 minutes). The link between visceral ischemic times and in-hospital outcomes, and visceral function biomarker levels were retrospectively analyzed through chi-square test, nonparametric analysis of variance, and cubic spline interpolation. Results: From 1995 to 2023, 1325 patients underwent aortic arch surgery under circulatory arrest at our center. Mild-to-moderate hypothermia (nasopharyngeal temperature ≥25°) was used in 960 cases. There was no significant difference among the groups for in-hospital death (group 1 = 8.5%, group 2 = 13.2%, group 3 = 11.3%; P = .224), renal complications (group 1 = 13.0%, group 2 = 19.7%, group 3 = 22.6%; P = .056), and gastrointestinal complications (group 1 = 5%, group 2 = 5.5%, group 3 = 7.1%; P = .696). However, respiratory complications (group 1 = 19.4%, group 2 = 28.1%, group 3 = 21.4%; P = .027) and transient dialysis (group 1 = 2.8%, group 2 = 7.8%, group 3 = 11.3%; P = .011) were linked to longer visceral ischemic times. Groups 2 and 3 presented significantly higher levels of creatinine (P < .01), glutamic-oxaloacetic transaminase (P < .05), and glutamic pyruvic transaminase (24 and 48 hours postsurgery, P < .01). Cubic spline analysis showed that the incidence of renal complications reached a minimum at a low visceral ischemic time and then consistently increased. Respiratory complications showed a maximum incidence at approximately 50 minutes of visceral ischemic time and then subsequently decreased. Conclusions: Mild-to-moderate hypothermia is a safe strategy for visceral organ protection regardless of visceral ischemic time. However, longer visceral ischemic times are linked to renal complications.