1 Department of Anaesthesia, National University Hospital, Singapore.
2 Magorium Private Limited, Singapore.
3 Department of Anaesthesia, National University Hospital, Singapore; Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
4 Department of Anaesthesia, National University Hospital, Singapore; Yong Loo Lin School of Medicine, National University of Singapore, Singapore. Electronic address: pei_kee@hotmail.com.