Effects of Stellate Ganglion Block on Delirium and Circadian Rhythm in Geriatric Intensive Care Patients

Delirium is a common complication in elderly intensive care unit (ICU) patients and is associated with poor clinical outcomes. Circadian rhythm disruption is considered an important contributing factor in delirium development. Stellate ganglion block (SGB) may modulate autonomic nervous system activity and improve circadian rhythm regulation. This prospective randomized placebo-controlled trial aims to evaluate the effects of ultrasound-guided stellate ganglion block on delirium incidence and circadian rhythm in ICU patients aged 65 years and older. Delirium will be assessed using validated clinical scales, and circadian rhythm will be evaluated through serial measurements of serum melatonin and plasma cortisol levels

Inclusion Criteria: * Patients aged 65 years or older expected to remain in the intensive care unit for more than 48 hours * RASS score \> -4 Exclusion Criteria: * History of neurodegenerative disease (e.g., Alzheimer's disease, dementia, vascular dementia) * Uncontrolled psychiatric disorders * Alcohol use disorder and/or substance abuse * History of traumatic brain injury or ischemic/hemorrhagic cerebrovascular event * Severe hearing and/or visual impairment * Benzodiazepine use * Renal failure (Acute Kidney Injury stage 2-3) and/or liver failure * Beta-blocker use * Contraindications to stellate ganglion block (e.g., coagulopathy, glaucoma, recent myocardial infarction) * Sepsis * Allergy to bupivacaine * Inability to communicate in Turkish or English * Severe hyponatremia * Hemodynamic instability