Postoperative diastolic perfusion pressure as a predictor of delirium after cardiac surgery

Postoperative delirium (POD) is a frequent neurological complication after cardiac surgery, associated with increased morbidity, prolonged hospitalization, and poor long-term outcomes. Diastolic perfusion pressure (DPP), reflecting the difference between diastolic arterial pressure and central venous pressure (CVP), plays a critical role in organ perfusion, yet its association with POD remains unclear. This study aimed to investigate the predictive value of postoperative DPP for POD in patients undergoing cardiac surgery with cardiopulmonary bypass.

In this retrospective case-control study, 4,418 adult patients who underwent cardiac surgery between May 2019 and December 2022 were analyzed. POD was assessed using the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU). Postoperative DPP was calculated as diastolic arterial pressure minus CVP, and the mean values during the first 6 and 12 postoperative hours (DPP_6h_mean, DPP_12h_mean) were extracted. Multivariable logistic regression, restricted cubic spline (RCS) analysis, and a predictive nomogram were used to evaluate the association between DPP and POD.

POD occurred in 352 patients (8.0%). Compared with those without POD, patients with delirium had significantly lower postoperative DPP values at both 6 and 12 h after surgery (all P < 0.001). In multivariable analysis, male sex, older age, higher APACHE II score, longer operation time, and lower DPP_12h_mean were independent predictors of POD. Each 5 mmHg decrease in DPP_12h_mean increased the risk of delirium by approximately 20% (adjusted OR = 1.20, 95% CI: 1.06-1.35, P = 0.004). The predictive model incorporating DPP_12h_mean achieved good discrimination (AUROC = 0.743) and clinical utility.

Lower postoperative diastolic perfusion pressure is independently associated with an increased risk of postoperative delirium after cardiac surgery. DPP may serve as a clinically useful marker reflecting effective organ perfusion. Optimization of DPP may represent a potential strategy for reducing delirium risk; however, this requires confirmation in prospective studies.