Before induction the investigators install an antecubital infusion line, an indwelling arterial blood pressure line, a Bisprectal Index (BIS) and a 3-lead ECG. The investigators give 2 millilitres of Lidocaine prior to infusion of Propofol 2 % to avoid pain during injection. Anaesthesia will be induced with a bolus of 200 milligrams or 350 milligrams of Propofol 2 % over 60 seconds delivered by a Graseby Medical 3400 pump. Patients are not given any premedication. During the bolus injection patients are asked to count. At the moment the patient stops counting a blinded observer notes the time and BIS and evaluates presence of the eyelash reflex. When the total amount of Propofol 2 % is given a blinded observer notes the BIS and presence of eyelash reflex and 250 micrograms of Fentanyl and 50 milligrams of Atracurium is given. The BIS is noted again and the patient will be intubated and mechanically ventilated. The ventilation modes are noted, as well as the amount of PEEP and when a pneumoperitoneum is used the investigators note the intra-abdominal pressure. The BIS monitors depth of anaesthesia continuously and data will be recorded at intervals of 30 seconds.