Inclusion Criteria:  * age > 18 years  Exclusion Criteria:  BMI index > 30 kg/m2 Known or suspected neuromuscular disorders impairing neuromuscular function; Allergies to muscle relaxants, anesthetics or narcotics; A (family) history of malignant hyperthermia or any other muscle disease; Any neurological or psychiatric illness (including a history of anxiety). ASA class 3 or higher Gastro-oesophageal regurgitation