Does Higher Temperature During Moderate Hypothermic Circulatory Arrest Increase the Risk of Paraplegia in Acute DeBakey I Aortic Dissection Patients?

Background: In this study, we sought to assess the safety of high-moderate (24.1-28.0°C) and low-moderate (20.1-24.0°C) systemic hypothermia during circulatory arrest (MHCA) in patients with acute DeBakey I aortic dissection (DeBakey I AAD), particularly concerning spinal cord protection.

Methods: From 2009 to 2020, 1759 patients with DeBakey I AAD who underwent frozen elephant trunk and total arch replacement surgery at a tertiary centre were divided into preoperative malperfusion (viscera, spinal cord, or lower extremities) and nonmalperfusion subgroups. The baseline differences were balanced with the use of propensity score matching. Prognoses were compared between those who were subjected to high-MHCA (nasopharyngeal temperature 24.1-28.0°C) and low-MHCA (nasopharyngeal temperature 20.1-24.0°C).

Results: In the nonmalperfusion subgroup (n = 1389), 469 pairs of matched patients showed lower in-hospital mortality and incidence of acute kidney injury in the high-MHCA group than in the low-MHCA group: in-hospital mortality 7.0% vs 10.2% (P = 0.01); acute kidney injury, 57.1% vs 64.6% (P < 0.01). The duration of mechanical ventilation was shorter in the high-MHCA group than that in the low-MHCA group (P = 0.03). No significant difference in the incidence of paraplegia was observed between the 2 groups. In the malperfusion subgroup (n = 370), 112 pairs of matched patients showed a higher incidence of paraplegia in the high-MHCA group than in the low-MHCA group (15.9% vs 6.5%; P = 0.04).

Conclusions: The safety of high-MHCA, a commonly used temperature management strategy during aortic arch surgery, was recognised in most patients with DeBakey I AAD. However, among patients with preoperative distal organ malperfusion, low-MHCA may be more appropriate owing to an increased risk of postoperative paraplegia associated with high-MHCA.