Haibo Zhang1,2,3,4
and Arthur S Slutsky1,2,5 
1
Keenan Research Centre at the Li Ka Shing Knowledge Institute of St Michael's Hospital, Bond Street, Toronto, ON, Canada
2
Interdepartmental Division of Critical Care Medicine, Division of Respirology, Department of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON, Canada
3
Department of Anaesthesia, University of Toronto, 1 King's College Circle, Toronto, ON, Canada
4
Department of Physiology, University of Toronto, 1 King's College Circle, Toronto, ON, Canada
5
King Saud University, BOX 2454, Riyadh 11451, Kingdom of Saudi Arabia