Anxiety is an emotional disorder. It's a painful concern caused by uncertainty. It is a complex phenomenon misunderstood in spite of medical progress. Relaxation is a technical for reduce anxiety and is effective and safe. Previous study demonstrated the impact of session relaxation on the autonomous nervous system by the heart rate variability.

Primary objective of this new study is to demonstrate a link between heart rate variability and reduced anxiety during relaxation session.

It is monocentric, prospective and interventional study. This study will be proposed at the patients who will have an orthopedic surgery in full hospitalization. These patients are anxious because of surgery too. The day before surgery anesthetist save heart rate variability and value of the partial pressure of carbon dioxide during relaxation session.

Inclusion Criteria:

• Affiliated or entitled to a social security
• Have signed consent before their participation in the study
• Aged over 18 years
• Patients who will have an orthopedic surgery in full hospitalization
• Patients anxious on visual analogic scale of anxiety (>5)

Exclusion Criteria:

• Different disorder : disability to understand instructions, respiratory insufficiency, obesity, sleep apnea, wearing a pacemaker
• Medical history of schizophrenia or bipolar disorder