Abstract: Risk factors of death in mechanically ventilated COVID-19 patients: a retrospective multi- center study Mohammadreza Salehi Department of Infectious Disease, Imam Khomeini Hospital complex, Tehran University of Medical Sciences Mohammad-Taghi Beig Mohammadi Department of Anesthesiology & critical care, Imam Khomeini Hospital complex, Tehran University of Medical Sciences Seyed Hamidreza Abtahi Department of pulmonary and critical care medicine, Thoracic Research Center, Imam Khomeini Hospital complex, Tehran University of Medical Sciences, Tehran. Iran Samrand-Fattah Ghazi Department of Anesthesiology & critical care, Imam Khomeini Hospital complex, Tehran University of Medical Sciences Abolfazl Sobati Department of nursing and midwifery, Tehran University of Medical Sciences. Clinical Nurse, Imam Khomeini Hospital Complex, Tehran, Iran Rama Bozorgmehr Shohada-e Tajrish Hospital, Shahid Beheshti University of Medical Sciences Seyed Ali Dehghan Manshadi Department of Infectious Disease, Imam Khomeini Hospital complex, Tehran University of Medical Sciences Saeed Reza Jamali Siahkali Department of Infectious Disease, Ziaeian Hospital, Tehran University of Medical Sciences Mostafa Mohammadi Department of Anesthesiology & critical care, Imam Khomeini Hospital complex, Tehran University of Medical Sciences Banafsheh Moradmand Badie Australasian Bone Marrow Transplant Recipient Registry (ABMTRR), Sydney, Australia Ensiyeh Rahimi (  ensiyehrahimi@gmail.com ) Department of Infectious Disease, Imam Khomeini Hospital complex, Tehran University of Medical Sciences Page 1/22 Research Article Keywords: COVID-19, mechanical ventilation, extubation, mortality risk factors Posted Date: March 11th, 2022 DOI: https://doi.org/10.21203/rs.3.rs-1362678/v1 License:   This work is licensed under a Creative Commons Attribution 4.0 International License. Read Full License Page 2/22 Abstract Introduction: Despite the improvement in COVID-19 therapeutic management the mortality of mechanically ventilated COVID-19 patients remains high. In this study, we determined risk factors of mortality in these cases. Methods: This retrospective study examined clinical and paraclinical data of COVID-19 patients mechanically ventilated at the time of hospitalization to ICU admission until death or discharge from hospital between April and September in 2021 in three COVID-19 referral hospitals. Results: One hundred twenty-five patients (60% male, mean age 62 ± 15.18, range 17 to 97 years old) were recruited to this study. 51(40%) survived and 74 (60%) didn’t survive. At the time of hospital admission, the vital signs were not significantly different between the survivors and non-survivors groups, also diarrhea was not reported in non-survivors, but reported in 9.5% of survivors (P = 0.02). The mean age of 74 non-survivors was higher than 51 survivors (65.1 ± 14.17 vs 56.9 ± 15.41, P = 0.003). The intubation time since the patients were admitted to hospitals was not significantly different between the two groups (3.38 ± 2.88 days vs 4.16 ± 3.42 days, P = 0.34). The mean LDH and D-dimer at the time of ICU admission were significantly higher in the non-survivors group (863 ± 449 vs 613 ± 326, P = 0.01; 4081 ± 3342 vs 542 ± 634, P = 0.009; respectively). However, the mean CRP was not significantly different between the two groups (76 ± 66.4, 54 ± 84.3; P = 0.1). Mean APACHE-II score was higher in the non-survivors than the survivors (15 vs 13; P = 0.01). Use of remdesivir,..