1 Department of Anaesthesia, National University Hospital, Singapore; Centre for Sustainable Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore. Electronic address: pei_kee@hotmail.com.
2 Department of Anaesthesia, National University Hospital, Singapore.
3 Department of Anaesthesia, National University Hospital, Singapore; Centre for Sustainable Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.