1 Division of Respiratory and Critical Care Medicine, Department of Medicine, National University Hospital, 1E Kent Ridge Road, NUHS Tower Block Level 10, Singapore, 119228, Singapore. kay_choong_see@nuhs.edu.sg.
2 Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore. kay_choong_see@nuhs.edu.sg.
3 Division of Critical Care - Respiratory Therapy, National University Hospital, Singapore, Singapore.