The Impact of a Beach Chair Position During Shoulder Arthroscopy on Regional Cerebral Oxygen Saturation : Comparison of Interscalene Block and General Anesthesia

Inclusion Criteria: Inclusion criterion for the study was the approval for surgery under general or regional anesthesia with ASA I and ASA II patients classification. - Exclusion Criteria: * The patients who have refused to take part in the study, patients assessed as ASA III or higher, who have cerebrovascular or coronary disease, coagulopathy, hypersensitivity to local anesthetics or other contraindications to one or the other type of anesthetic techniques All patients in whom the operation lasted less than 20 minutes or longer than 90 minutes, have been also excluded from the study.