The acute respiratory distress syndrome after out-of-hospital cardiac arrest: Incidence, risk factors, and outcomes

Objective: To define the incidence of the acute respiratory distress syndrome (ARDS) following out-of-hospital cardiac arrest (OHCA) and characterize its impact on outcome. Methods: This was a retrospective cohort study conducted at two urban, tertiary, academic hospitals from 2007 to 2014. We included adults with non-traumatic OHCA and survived for >= 48 h. Patients who received mechanical ventilation for >= 24 h, had 2 consecutive arterial blood gases with a ratio of the partial pressure of oxygen to the fraction of inspired oxygen <= 300, and bilateral radiographic opacities within 48 h of hospital admission were defined as having ARDS. We examined the associations between ARDS and outcome using multivariable analyses and performed sensitivity analyses excluding patients with evidence of cardiac dysfunction. Results: Of 978 OHCA patients transported to the study hospitals, 600 were mechanically ventilated and survived >= 48 h. A total of 287 (48%, 95% CI 44-52%) met criteria for ARDS within 48 h of admission. There were no differences in demographics, OHCA etiology, or cardiac rhythm according to ARDS status. Patients with ARDS had higher hospital mortality, longer ICU stays, more ventilator days, and were less likely to survive with full neurologic recovery. Upon excluding patients with cardiac dysfunction, the incidence of ARDS was unchanged. Conclusion: Nearly half of initial OHCA survivors develop ARDS within 48 h of hospital admission. ARDS was associated with poor outcome and increased resource utilization. OHCA should be considered among the traditional ARDS risk factors.