Inclusion Criteria:  Non-obese (BMI<27) American Society of Anesthesiologists (ASA) I and II (classification of the American Society of Anesthesiologists) adult patients Undergoing an orthopedic surgery Under general anesthesia Supine position  Exclusion Criteria:  History of allergy, intolerance, or reaction to propofol or to sufentanil or hypersensitivity to either drug History of allergy, intolerance or reaction to sevoflurane or hypersensitivity to this drug History of malignant hyperthermia to sevoflurane or other halogenated gaz History of allergy, intolerance, or reaction to cisatracurium or hypersensitivity to this drug Any history of neurologic, neurovascular, neurosurgical, or psychiatric active pathology within past 6 months History of allergy to egg, soy, or lecithin Uncontrolled arterial hypertension Unstable cardiac status (life-threatening arrhythmias, abnormal cardiac anatomy, significant cardiac dysfunction) Concomitant use of opioids, b-receptor antagonist, a2-receptor agonist or calcium channel blocker Currently receiving pharmacological agents for hypertension or cardiac disease Currently receiving or has received digoxin within the past 3 months BMI >28 kg m² Active, uncontrolled gastro-oesophageal reflux - an aspiration risk Current (or within past 3 months) history of apnea requiring an apnea monitor Craniofacial anomaly, which could make it difficult to effectively establish a mask airway for positive pressure ventilation if needed Active, current respiratory issues different from the baseline status (pneumonia, exacerbation of asthma, bronchiolitis, respiratory syncytial virus) Refusal of insertion of intravenous catheter while awake Patient refusal to participate in the study Cerebro-motor retardation / Mental disability / Psychological dependence / Legal guardianship