1. Columbia-Presbyterian Medical Center; Division of General Medicine, PH-9 East Room 105; 622 West 168th Street New York NY USA 10032
2. McGill University Health Centre; Respiratory Division, Department of Medicine; Montreal Chest Institute 3650 St-Urbain Montreal QC Canada H2X 2P4
3. Massachusetts General Hospital; Department of Emergency Medicine; 326 Cambridge St, Suite 410 Boston Massachusetts USA 02114