Hypothermic Circulatory Arrest Is Associated with Increased Risk of Postoperative Delirium: A Retrospective Cohort Study

Objectives: This study aimed to measure the incidence of postoperative delirium (POD) after aortic arch surgery with hypothermic circulatory arrest (HCA), compare it to cardiac surgeries not requiring HCA, and investigate whether neuroprotection subgroups displayed different incidences. Design: Retrospective cohort study Setting: Single academic medical center Participants: Patients over 18 years old undergoing cardiovascular surgery between July 2020 and May 2022, requiring cardiopulmonary bypass with HCA (n = 165) or without HCA (n = 1974). Interventions: HCA with various neuroprotection strategies including deep hypothermia (DHCA,14.1ºC - 20ºC), moderate hypothermia (MHCA, 20.1 - 28ºC), no cerebral perfusion (NCP), antegrade cerebral perfusion (ACP), or retrograde cerebral perfusion (RCP). Measurements and Main Results: POD was assessed on postoperative days one through five, using the Confusion Assessment Method. POD occurred in 51 (30.9%) patients in the HCA group and 225 (11.4%) patients in the non-HCA group (odds ratio 1.93; 95% CI: 1.24-2.97, p=0.003). Patients who underwent DHCA had a higher incidence of POD than those who underwent MHCA (40.2% vs. 16.7%, p = 0.001). There was no statistically significant difference in the incidence of POD between patients in the NCP, ACP and RCP subgroups. Conclusions: Postoperative delirium is more common following aortic arch surgery with HCA, particularly DHCA, compared with non-aortic arch surgery. Aortic arch surgery with HCA is associated with higher incidence of cardiopulmonary and renal complications. Additional studies are needed to identify interventions that improve postoperative neurocognitive outcomes in this high-risk patient population.