Impact of intraoperative blood pressure, blood pressure fluctuation, and pulse pressure on postoperative delirium in elderly patients with hip fracture: A prospective cohort study.

AIM: Postoperative delirium (PD) is a frequent complication of hip fracture surgery, but its pathophysiology remains poorly understood. We investigated the impact of a single episode of intraoperative hyper/hypotension, blood pressure (BP) fluctuation (ΔMAP), and pulse pressure (PP) on hyper/hypoactive PD in elderly patients undergoing surgery for hip fracture. We also assessed the effect of PD on clinical outcomes. METHODS: This was a prospective 1-year follow-up study of patients over 60 years of age with a primary diagnosis of acute low-energy hip fracture. Perioperative delirium was assessed using the Confusion Assessment Method (CAM); the development of PD and the type, hyperactive or hypoactive PD, were recorded. Cognitive assessment was evaluated using the Short Portable Mental Status Questionnaire (SPMSQ). The lowest and highest BP values were extracted from the patients' anaesthesia charts. Postoperative complications, reinterventions and 1-month mortality were recorded. RESULTS: PD occurred in 148 (53%) patients during the first postoperative week, with 75% of the cases diagnosed as hypoactive PD. Patients developing PD of any type were older, had a lower body mass index, higher SPMSQ and Charlson scores, more severe systemic diseases, a lower lowest intraoperative BP, a higher ΔMAP, a lower PP, and a higher postoperative pain score. They also took more drugs and received more blood transfusion intraoperatively. Multivariate logistic regression analyses showed that a higher MAP min had a protective effect on the occurrence of any type of PD, as well as hypoactive and hyperactive. PD had negative effect on outcomes. CONCLUSION: Our results provide evidence of an association between maximal hypotension, the lowest intraoperative mean blood pressure (MAP), ΔMAP, PP, and PD. A progressive decrease in MAP during surgery was associated with the increased odds of developing either type of PD.