Remote Ischemic Preconditioning and Postoperative Neuronal Injury

Inclusion criteria: * patients (≥50 years) scheduled for elective non-cardiac surgery with general anesthesia * patients at risk for postoperative delirium, defined as the presence of ≥2 of the following established risk factors: age ≥65 years, American Society of Anesthesiologists physical status classification of ≥III, Charlson Comorbidity, planned surgical duration \>180 minutes, polypharmacy (regular intake of more than five medications), symptoms of depression (Patient Health Questionnaire-9 ≥10 points) Exclusion criteria: * patients in whom RIPC cannot be safely applied due to relevant peripheral arterial disease (defined as Fontaine stage ≥II), lymphedema, recent upper-arm surgery, trauma, or skin lesions at the arm * patients with acute coronary syndrome (within the past month) * patients with surgery in the previous month * patients with intracranial surgery * patients with pre-existing delirium * patients with severe cognitive impairment preventing reliable delirium assessment * patients with current treatment with sulfonamides due to potential interference with ischemic preconditioning mechanisms * patients with previous participation in the SHIELD trial