ABSTRACT 437

Abstract

Background and aims: Diffuse alveolar damage (DAD) is the distruption of alveolar barriers and gas exchange due to overactive pulmonary inflammation. Pathological examination of acute respiratory distress syndrome (ARDS) patients reveals diffuse alveolar damage. Aims: To study the correlation between clinical criteria and severity of pathological findings, patients with diffuse alveolar damage in postmortem histological examination were evaluated. Methods: The study included 20 patients who were histologically diagnosed (postmortem) as diffuse alveolar damage. ARDS criteria and other clinical parameters were noted. Pulmonary tissues were evaluated for DAD findings; hyalen membranes, type 1 alveolar cell necrosis, endothelial cell necrosis, inflammation, edema, type 2 alveolar cell proliferation and fibrosis. Severity of DAD was graded. Results: Fibrosis was not present in any sample, inflammation (infection) markers were common. Patients were classified according to fulfilment of clinical criteria and severity of pathological findings (mild-medium severity vs high severity). 55% of patients met 1994 AECC criteria, whereas only 41% met 2012 Berlin criteria. Evaluation of alveolar damage revealed that clinical criteria could not foresee pathological severity. Clinical parameters, scores, PaO2/FiO2 ratio (one of the clinical criteria) have not been statistically correlated with pathological severity. Oxygenation index, based on mean pressure and FiO2 needed for oxygen consumption, seems to be higher in patients who meet clinical ARDS criteria than who do not, and higher in patients who have more severe DAD than milder DAD. Conclusions: Oxygenation index, alongside clinical criteria, may be a valuable tool in predicting pulmonary damage severity.