Clinical differences between pulmonary and extrapulmonary acute respiratory distress syndrome: a retrospective cohort study o f prospectively collected data in Japan

Background: Although acute respiratory distress syndrome (ARDS) reportedly shows various clinical phenotypes with different risk and prognostic factors, few studies have assessed the clinical features and prognosis of pulmonary and extrapulmonary ARDS. The aim of the present study was to investigate clinical differences between pulmonary and extrapulmonary ARDS. Methods: In total, 200 patients who met the Berlin criteria and were diagnosed with ARDS between October 2004 and September 2017 were included. We classified the patients into pulmonary and extrapulmonary ARDS groups. Both groups were assessed for 60-day mortality, duration of ventilation, and other clinical features. Results: There were 150 and 50 patients in the pulmonary and extrapulmonary ARDS groups, respectively. The two groups showed no significant differences in any assessment parameters except the serum lactate dehydrogenase (LDH) level, which was higher in the extrapulmonary ARDS group (P=0.01). After adjustment for potentially confounding covariates, there were no significant differences in 60-day mortality (P=0.99) and the duration of ventilation (P=0.45) between the two groups. Mortality was significantly associated with the disseminated intravascular coagulation (DIC) score, high-resolution computed tomography (HRCT) score, and serum LDH level in the pulmonary ARDS group and the DIC score and HRCT score in the extrapulmonary ARDS group. Conclusions: Pulmonary and extrapulmonary ARDS may be comparable in terms of the prognosis and duration of ventilation. DIC and HRCT scores may be common clinical predictors of mortality with ARDS.