1. Microscopic Section of Human Lung from Phosgene Poisoning (See Plate 1)
Death occurred at the nineteenth hour after exposure to the gas.
The piece of lung shown is almost entirely useless for aeration of the blood. Most of the pulmonary alveoli are filled with oedema fluid, and the walls of the air sacs are burst asunder in many places. The rounded edges of these torn walls can be recognized both in the areas of emphysema and in the parts that are flooded with oedema fluid. The bronchus is also filled with oedema fluid, but it should be noted that its lining epithelium is intact and pus cells have not accumulated in the secretion. The blood vessels of the alveolar network are congested; intravascular thrombosis is frequently found in these smaller vessels, though it is not actually shown in the area of this section.
The main changes in the lung are
(i) Congestion, and occasional thrombosis, of the network of pulmonary blood vessels.
(ii) Abundant outpouring of inflammatory oedema fluid both into the tissues and into the air spaces of the alveoli and bronchi.
(iii) Disruptive emphysema of the weakened lung tissue.
The result of these changes is that the blood circulation through the lungs is impeded, and the respiratory exchange of gases between the blood and the air in the lung is seriously diminished. The affected person is in danger of death by asphyxia so long as his lung is drowned in oedema fluid.
From the third day onwards the oedema fluid is either reabsorbed or expectorated, and the lung soon resumes its functions. Bronchopneumonic complications may develop from. secondary infections, but they are not common.
The recovery of the lung, even after severe gassing, appears to be functionally good. In the earlier stages of convalescence there may still be signs of persisting oxygen want, so that tachycardia with excessively rapid respiration is the result of even slight physical effort. Later these disabilities vanish. The microscopic examination of lungs in these stages of recovery has not been made.