Morphometric investigation of emphysema aquosum in the elderly.

We compared the lungs of six drowned and six non-drowned persons over 70 to determine whether there is evidence of acute overinflation in drowning that can be distinguished from senile lung emphysema. All left lungs underwent intrathoracic formalin fixation to preserve their state of insufflation. To assess the effects of lung collapse, all right lungs were sectioned as usual and then immersed in formalin. After histological processing, microphotography and image processing of 12 specimens per corpse, 50 binary images of each specimen were measured by computerized morphometry. Intrathoracic fixation resulted in significantly less tissue area (and more airspace) in the left than in the right lungs of both groups. Comparing both groups' left lungs revealed that the interalveolar septa were thinner and the area occupied by connecting nodes smaller in drowning; these single nodes also tended to be smaller. There was a tendency for less alveolar tissue area per image in drowning than in control lungs and for narrow tissue structures to comprise a higher percentage of both the total tissue area and total tissue perimeter per image. We conclude that there is morphological evidence of acute overinflation even in senile lungs, but this is masked by postmortem lung collapse as suggested by the overlapping values of the right lungs. Support to the diagnosis of drowning among drowned elderly patients can only be available in lungs subjected to intrathoracic postmortem fixation.