Correlation between middle cerebral artery flow parameters and postoperative delirium in older non-cardiac patients: study protocol for a single-centre, prospective, observational study.

backgroundPostoperative delirium (POD) is a common postoperative complex syndrome in older patients, which can lead to prolonged hospital stay, increased mortality and long-term cognitive decline as well as severely affect the prognosis and survival of affected individuals. Currently, the identification of POD mostly depends on clinical observation and scale measurement, which have limitations such as strong subjectivity and long assessment time. Therefore, screening for objective and effective detection indicators is crucial. This study will employ transcranial Doppler ultrasound (TCD) to collect preoperative middle cerebral artery (MCA) flow parameters to evaluate their correlations with POD, which may serve as an objective basis for evaluating POD. These findings may aid in the early identification of high-risk patients and provide a scientific basis for the early intervention and treatment of POD. METHODS AND ANALYSIS: This study is a prospective, observational cohort investigation. Preoperative assessment, including patient baseline data, laboratory blood tests, TCD examination and cognitive evaluation, as well as obtaining informed consent, will be completed the day before surgery. The following patient data will be recorded: age, gender, body mass index, educational background, comorbidities, Mini-Mental State Examination score, American Society of Anesthesiologists grade, surgery duration, preoperative laboratory blood tests and MCA flow parameters. The primary endpoint measure is the incidence of POD, which will be assessed using the 3-Minute Diagnostic Interview for Confusion Assessment Method scale during a postoperative evaluation period of 7 days. The secondary endpoint is the POD typing, POD severity and occurrence of postoperative adverse events. This study aims to enrol 250 patients. Univariate and multivariate logistic regression analyses will be conducted to explore the factors associated with POD. The cut-off value obtained using the receiver operating characteristic curve will be used to evaluate the diagnostic value of individual or combined indexes. ETHICS AND DISSEMINATION: This study was approved by the Ethics Committee of the Affiliated Hospital of Jiaxing University (2025-KY-108-003). All patients in this study will provide written informed consent. The study results will be published in an open-access format. This study does not include an independent data monitoring committee because it is an observational and low-risk investigation. TRIAL REGISTRATION NUMBER: ChiCTR2500098949.