Characteristics of Nonpulmonary Organ Dysfunction at Onset of ARDS Based on the Berlin Definition.

BACKGROUND

The Berlin definition of ARDS does not account for nonpulmonary organ failure, which is a major determinant of outcome. We examined whether an increasing severity of hypoxemia across the Berlin definition classifications also corresponded with evidence of multiple organ dysfunction on the day of ARDS onset. We also examined the representation of major etiologies for ARDS across the Berlin definition classifications.

METHODS

This single-center, retrospective study examined 15 years of data from a quality assurance program that monitored the use of lung-protective ventilation in ARDS. We analyzed 1,747 subjects without chronic kidney disease or severe chronic liver disease at ARDS onset. The most abnormal laboratory values at ARDS onset were analyzed as cutoff values to assess organ dysfunction. Data were analyzed by using non-parametric analysis of variance (Kruskall-Wallis test) and the Dunn post test. Categorical variables were compared by using the Fisher exact test. Alpha was set at 0.05. Factors independently associated with mortality were assessed by multivariate logistic regression modeling.

RESULTS

Nonpulmonary organ dysfunction was present in at least 1 system at ARDS onset that increased with severity: 80% (mild), 83% (moderate), and 90% (severe). ARDS etiologies varied as severity increased: trauma-associated lung injury steadily decreased, whereas lung injury associated with aspiration and pneumonia steadily increased. Hospital mortality also increased significantly with the Berlin definition classifications: mild (22%), moderate (30%), and severe (47%). Multivariate logistic regression modeling revealed that the Berlin definition of severe ARDS was independently associated with mortality, as were cutoff values for renal and hepatic function as well as acidemia. Normal hematologic function and the absence of standard exclusion criteria used for therapeutic clinical trials in ARDS were protective.

CONCLUSIONS

Nonpulmonary organ dysfunction was present at ARDS onset in most subjects and was more pronounced as ARDS severity increased. The Berlin definition classification of ARDS provided an elegant scheme for studying the syndrome because it coincided with increasing multiple organ dysfunction.