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