SPI-guided Analgesia During CEA Under RA

Inclusion Criteria: clinical diagnosis of stenosis of carotid artery written consent to participate in the study written consent to undergo carotid endarterectomy under regional anaesthesia of cervical plexus using Moore's technique general heath condition I-III of American Society of Anaesthesiology Exclusion Criteria: * necessity of administration of vasoactive drugs influencing SPI monitoring pregnancy * anatomical malformation that make monitoring using SE sensor impossible * general atherosclerosis and heart rhythm disturbances impairing SPI monitoring * chronic medication using opioid drugs leading to resistancy to opioids. * farmacotherapy with anticoagulants * allergy to local anaesthetics