1. 1Department of Anesthesiology, Singapore General Hospital, Singapore.
2. 2Department of Surgical Intensive Care, Singapore General Hospital, Singapore; Anesthesiology and Perioperative Sciences Academic Clinical Programme, Duke-National University of Singapore Graduate Medical School, Singapore.
3. 3Department of Surgical Intensive Care, Singapore General Hospital, Singapore; Department of Cardiothoracic Anesthesia, National Heart Center, Singapore; Anesthesiology and Perioperative Sciences Academic Clinical Programme, Duke-National University of Singapore Graduate Medical School, Singapore.
4. 4Department of Pain Medicine, Singapore General Hospital, Singapore; Anesthesiology and Perioperative Sciences Academic Clinical Programme, Duke-National University of Singapore Graduate Medical School, Singapore.