Inclusion Criteria:

• ASA status 1,2.

  • Age 18 years or older
  • Elective shoulder arthroscopic surgery under general anesthesia and nerve block performed preoperatively.

Exclusion Criteria:

• • Patient refusal

  • Serious cardiac arrhythmias (including atrial fibrillation) or unstable coronary artery disease.
  • Use of drugs that act on the autonomic nervous system (including β- blockers).
  • Coagulation disorders..
  • Anatomical disorders and/or neuropathic disease.
  • BMI above 40.
  • History of substance abuse.
  • Chronic use of psychotropic and/or opioid.
  • History of psychiatric diseases needing treatment.
  • Allergy to any drug in the study protocol.
  • Failure of nerve block performed in the preoperative block room when tested prior to entering the operating room (i.e. lack of loss of sensation to ice at the shoulder incision level).