Inclusion Criteria:  Patients classified as American Society of Anesthesiology physical status (ASA PS) classes I, II or III Aged between 18 and 70 years Scheduled for radiofrequency ablation of liver tumours under general anaesthesia with an expected surgery duration shorter than 60min  Exclusion Criteria:  Allergy to rocuronium Myasthenia gravis Guillain-Barre ́ syndrome Duchenne muscular dystrophy or similar Receiving drugs that might interfere with the neuromuscular transmission or the response to neuromuscular blockers, such as some anticonvulsants and antibiotics