Acidosis as one of the delivering factors of alveolar macrophages during suffocation.

When death by suffocation occurs, the histological appearance of the lungs depends on the length of time between the beginning of suffocation and death. In cases of acute asphyxia the histological appearance is restricted to congestion of the capillaries and veins, dispersed scattered foci of bleeding into the alveoli and, occasionally, foci of oedema. In cases of protracted suffocation, because of the longer time-interval between the beginning of suffocation and death, the congestion of capillaries and veins is greater, more haemorrhages in the alveoli are found and more oedema is produced. Moreover, in the alveolar spaces, free alveolar cells and multinucleated giant cells, typical of protracted suffocation, can be observed. A sufficient stimulus to produce the appearance of alveolar cells is neither the want of oxygen itself nor the changes of pH which develop during protracted suffocation.