During laparoscopic bariatric surgery, adequate muscle relaxation is important to maintain good surgical conditions. To achieve this muscle relaxation, neuromuscular transmission blocking agents, such as rocuronium (Esmeron®) are used. It sometimes happens that there is still some neuromuscular blocking activity left in the patient on awakening from anesthesia. This is called residual curarization and is known to cause postoperative complications such as impairment of respiratory function.