Acute respiratory distress syndrome in wartime military burns: application of the Berlin criteria

Abstract

Background: Acute respiratory distress syndrome (ARDS) prevalence and related outcomes in burned military casualties from Iraq and Afghanistan have not been described previously. The objective of this article was to report ARDS prevalence and its associated in-hospital mortality in military burn patients.

Methods: Demographic and physiologic data were collected retrospectively on mechanically ventilated military casualties admitted to our burn intensive care unit from January 2003 to December 2011. Patients with ARDS were identified in accordance with the new Berlin definition of ARDS. Subjects were categorized as having mild, moderate, or severe ARDS. Multivariate logistic regression identified independent risk factors for developing moderate-to-severe ARDS. The main outcome measure was the prevalence of ARDS in a cohort of patients burned as a result of recent combat operations.

Results: A total of 876 burned military casualties presented during the study period, of whom 291 (33.2%) required mechanical ventilation. Prevalence of ARDS in this cohort was 32.6%, with a crude overall mortality of 16.5%. Mortality increased significantly with ARDS severity: mild (11.1%), moderate (36.1%), and severe (43.8%) compared with no ARDS (8.7%) (p < 0.001). Predictors for the development of moderate or severe ARDS were inhalation injury (odds ratio [OR], 1.90; 95% confidence interval [CI], 1.01-3.54; p = 0.046), Injury Severity Score (ISS) (OR, 1.04; 95% CI, 1.01-1.07; p = 0.0021), pneumonia (OR, 198; 95% CI, 1.07-3.66; p = 0.03), and transfusion of fresh frozen plasma (OR, 1.32; 95% CI, 1.01-1.72; p = 0.04). Size of burn was associated with moderate or severe ARDS by univariate analysis but was not an independent predictor of ARDS by multivariate logistic regression (p > 0.05). Age, size of burn, and moderate or severe ARDS were independent predictors of mortality.

Conclusion: In this cohort of military casualties with thermal injuries, nearly a third required mechanical ventilation; of those, nearly one third developed ARDS, and nearly one third of patients with ARDS did not survive. Moderate and severe ARDS increased the odds of death by more than fourfold and ninefold, respectively.

Level of evidence: Epidemiologic/prognostic study, level III.