1. College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
2. The School of Medicine and Health Sciences, George Washington University, Washington, USA
3. Department of Medicine, Security Forces Hospital, Riyadh, Saudi Arabia
4. Department of Emergency, King Faisal General Hospital, Makkah, Saudi Arabia
5. Department of Thoracic Surgery, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia