1. Critical Care Quality Improvement Research Center, Loghman Hakim Hospital , Shahid Beheshti University of Medical Sciences , Tehran , Iran
2. Critical Care Quality Improvement Research Center, Shahid Modarres Hospital , Shahid Beheshti University of Medical Sciences , Tehran , Iran
3. Critical Care Quality Improvement Research Center, Dr. Masih Daneshvari Hospital , Shahid Beheshti University of Medical Sciences , Tehran , Iran
4. Department of Health Management and Economics, Faculty of Medicine , Aja University of Medical Sciences , Tehran , Iran