Clinical Research Directory

Inclusion Criteria: * Patients, age 18 to 65 years inclusive * American Society of Anesthesiology \[ASA\] status I or II * Body mass index 19 - 30 kg/m2 * Patient scheduled for elective surgery lasting ≥ 60 minutes * Patient is able to read and understand the information sheet and to sign and date the consent form. * Negative urinary or serum pregnancy test (not applicable if status post hysterectomy or tubal ligation or menopausal woman) Exclusion Criteria: * Surgery with need for neuromuscular block * Contraindication for general anesthesia with laryngeal mask airway, such as gastro-oesophageal reflux. * Hypersensitivity or allergy to magnesium sulfate or propofol * Contraindication to volatile anesthetics such as malignant hyperthermia * Patients with neuromuscular disease * Patients receiving medications known to influence neuromuscular function (for instance, aminoglycosides or phenytoine) * Known electrolyte abnormalities (for instance, hypermagnesemia) * Atrioventricular heart block * Patients with magnesium treatment within 48 hours before start of study * Liver insufficiency (bilirubine \<1.5x, ALAT/ASAT\<2.5x the upper limit of normal value) * Renal insuffisancy (créatinine \<1.5x upper limit of normal value, clearance\<30ml/minute) * Patient having participated in any clinical trial within 30 days, inclusive, of signing the informed consent form of the current trial. * Pregnant or breast-feeding women.