(210) Low Mean Arterial Pressure Is Not Associated With Postoperative Delirium in Cardiac Surgery Patients

Introduction: Delirium affects 26-52% of cardiac surgery patients, leading to extended mechanical ventilation, longer ICU stays, and increased mortality. Identifying adjustable risk factors such as blood pressure could enhance outcomes. Prior studies give mixed evidence about how perioperative hypotension impacts postoperative delirium. There's also no universal definition for hypotension, complicating the issue. Therefore, comprehending the link between low MAP and postoperative delirium risk is essential.

Methods: We carried out a retrospective review of adult patients undergoing cardiac surgery involving cardiopulmonary bypass from 2017 to 2020. Our aims were to examine the connection between intraoperative hypotension and postoperative delirium, and to pinpoint the Low MAP associated with a higher postoperative delirium rate. We included patients aged 18 or older having valve surgery, CABG, aortic procedures, or a combination, excluding those who had off-bypass CABG or procedures requiring hypothermic circulatory arrest. Data were collected from electronic medical records, with delirium defined via the ICU-CAM or bCAM, observed 12 to 96 hours post-surgery. We used multivariable logistic regression models, adjusted for demographics, co-morbidities, and procedure, to evaluate the relationship between low MAP and postoperative delirium. Low MAP's added diagnostic value was measured using likelihood ratio tests.

Results: Low MAP was approximately normally distributed (Figure 1). We found no confounder-adjusted association between Low MAP and post-operative delirium risk at any time period. These results are demonstrated by nearly flat spline curves (Figure 2), although MAP > 80mmhg was seen to have a significant positive correlation with delirium in unadjusted analysis. Likelihood ratio tests were not statistically significant (all P>0.05).

Conclusions: These data provide no evidence that Low MAP increases risk for postoperative delirium in patients undergoing cardiac surgery.