Morphometric differences in pulmonary lesions in primary and secondary ARDS - A preliminary study in autopsies

The present study was undertaken in order to describe the morphological dif ferences between pulmonary lesions in acute respiratory distress syndrome o riginating from direct pulmonary injury (ARDSp) and those originating from extrapulmonary injury (ARDSexp). We investigated a total of 38 ARDS-patients (27 males) ran-inc, in age from 19 to 75 years, classified according to underlying disease in pulmonary (A RDSp) and extrapulmonary disease (ARDSexp). The extent of acute diffuse alv eolar damage was assessed morphometrically on histologic gross sections in the upper and lower lobes of one lung. The lesions showed quantitative differences in extent and distribution acco rding to underlying disease (primary pulmonary or secondary involvement). In pulmonary ARDS, a predominance of alveolar collapse (16.6% +/- 12.3% ver sus 10.3% +/- 11.9%, p = 0,03), fibrinous exudate (1.7% +/- 3.2% versus 0.4 % +/- 1.1%, p = 0.01) and alveolar wall edema (11.2% +/- 7.4% versus 6.6% /- 4.4%, p = 0,05) were found compared to extrapulmonary ARDS. We conclude that the morphology of acute diffuse alveolar damage (DAD) is m ainly determined by underlying disease (pulmonary ARDS or extrapulmonary AR DS) differing in quantitative terms within the lung. Physiological, radiogr aphic and respiratory system mechanics differences described in ARDSp and A RDSexp may therefore be due to morphometric differences in pulmonary lesion s.