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

Delirium is a common and serious complication among elderly intensive care unit (ICU) patients and is associated with increased morbidity, mortality, prolonged hospitalization, and poor long-term outcomes. Although the pathophysiology of delirium is multifactorial, growing evidence suggests that disruption of circadian rhythm and autonomic nervous system imbalance play an important role in its development. Current pharmacological and non-pharmacological treatment strategies remain limited, highlighting the need for novel preventive and therapeutic approaches.

Stellate ganglion block (SGB) is an ultrasound-guided autonomic modulation technique that has been shown to influence sympathetic activity, sleep regulation, and circadian rhythm. However, its potential role in reducing ICU delirium and modulating circadian biomarkers has not been clearly established.

This study is designed as a prospective, randomized, placebo-controlled to investigate the effects of ultrasound-guided stellate ganglion block on delirium and circadian rhythm in geriatric ICU patients. Eligible patients aged 65 years and older will be randomized in a 1:1 ratio to receive either stellate ganglion block with 0.5% bupivacaine or placebo saline injection. Randomization will be computer-generated, and outcome assessors will be blinded to group allocation.

Delirium will be assessed twice daily for seven days using validated clinical tools, including the Richmond Agitation-Sedation Scale (RASS) and Confusion Assessment Method for the ICU (CAM-ICU). Delirium severity will be evaluated using the Delirium Rating Scale-Revised-98, and motor subtypes (hyperactive, hypoactive, mixed) will be categorized according to RASS scores. Sleep quality will be assessed using the Richards-Campbell Sleep Questionnaire.

To evaluate circadian rhythm, serum melatonin and plasma cortisol levels will be measured at predefined circadian time points during the first three days following ICU admission. The study combines objective biomarker assessment with standardized delirium evaluation to explore potential mechanistic pathways linking autonomic modulation and neurocognitive outcomes.

The primary objective is to determine whether stellate ganglion block reduces delirium incidence in elderly ICU patients. Secondary objectives include evaluating delirium severity, motor subtype distribution, sleep quality, circadian biomarker changes, and ICU and hospital length of stay. This trial aims to provide mechanistic and clinical evidence regarding the potential role of stellate ganglion block in ICU delirium management.

• Serum melatonin circadian pattern [Time frame: From ICU admission to Day 3 (samples collected at predefined circadian time points: 03:00, 08:00, and 16:00)]
• Plasma cortisol circadian pattern [Time frame: From ICU admission to Day 3, measured three times daily at predefined time points (03:00, 08:00, and 16:00).]
• Delirium severity (Delirium Rating Scale-Revised-98 score) [Time frame: From the first diagnosis of delirium until Day 7 of ICU stay or ICU discharge, whichever occurs first, assessed daily.]
• Delirium motor subtype distribution [Time frame: From the first diagnosis of delirium until Day 7 of ICU stay or ICU discharge, whichever occurs first, assessed daily.]
• Sleep quality (Richards-Campbell Sleep Questionnaire score) [Time frame: From ICU admission to Day 7 of ICU stay or ICU discharge, whichever occurs first, assessed daily.]
• ICU and hospital length of stay [Time frame: From hospital admission to discharge home or in-hospital death, whichever occurs first, calculated as total days of hospitalization, assessed up to 60 days.]