Effect of Erector Spinae Plane Block on Cerebral Oxygenation During One-Lung Ventilation

Inclusion Criteria: * Patients aged 18-80 years * With an American Society of Anesthesiologists (ASA) physical status of I-III * Glasgow Coma Scale (GCS) score of 13-15 * Scheduled for thoracic surgery requiring one-lung ventilation Exclusion Criteria: * Patients undergoing emergency surgery * Those younger than 18 years or older than 84 years * Patients with an American Society of Anesthesiologists (ASA) physical status of IV or V * Patients who refused to participate in the study * Those with a history of brain surgery for any reason * Patients with defects in the frontal region preventing placement of near-infrared spectroscopy probes * Patients with distorted thoracic vertebral anatomy for any reason resulting in inadequate ultrasonographic imaging for block performance * Patients with a known allergy to local anesthetics * Patients with neurological disorders such as Alzheimer's disease or dementia * Patients who were illiterate and/or unable to establish effective communication