 6. Postoperative sedation: following skin closure, all anaesthesia agents will be ceased. A low dose propofol infusion will be permitted for postoperative ICU sedation until they are suitable for extubation.The aim is for a Ramsay sedation score of 2 upon initial return to ICU then once haemodynamically stable, to aim for a score of 4. Patients will be escorted to the intensive care unit and will be ventilated until they have achieved accepted standard criteria for extubation awake and co-operative, warm, haemodynamically stable, PaCO250mmHg, PaO2 100 on FiO2 0.4. Patients will be allowed to awaken in ICU and extubated. 