 Repair of thoraco-abdominal aortic aneurysms TAA is mostly performed in specialized centers. These centers report an operative mortality around 10. In an analysis of 337 consecutive TAA, Cambria et al reported pulmonary 44, cardiac, 13.8 renal 13.5 and postoperative spinal cord deficit as prominent complications. Due to the extent of the surgery and the high risk of complications, all these patients require post- operative care in the Intensive Care Unit ICU. In 2003, the operation was performed in approximately 40 patients at the Massachusetts General Hospital MGH. The median length of stay in the ICU was 7 days range 2-55 All patients required postoperative mechanical ventilation for greater than 48 h. During this period, a continuous intravenous infusion of propofol is normally used for sedation. Pain relief is provided by a continuous intravenous infusion of hydromorphone. This combination of sedation and analgesia is widely used at MGH and other institutions. Although very effective, it may cause respiratory depression and a deep sedative state, which may result in a prolonged requirement for mechanical ventilation. Lighter or more controllable sedation appears to be beneficial in this regard: daily wake up of intubated and sedated ICU patients decreases days on the ventilator and length of stay in the ICU. 