Prior to the introduction of the treatment now prevalent for carbon monoxide asphyxia by means of inhalation of carbon dioxide and oxygen,1 pneumonia was one of the recognized sequels of severe but not immediately fatal gassing.2 It is therefore a suggestive fact that, among cases treated by inhalation of carbon dioxide, postasphyxial pneumonia does not occur. Among hundreds of cases thus treated, of which we have records, there is not a single report of a subsequent pneumonia.
In this laboratory a few years ago it was found also, as previously observed by Oliver,3 that dogs after prolonged asphyxia may develop a condition of acute congestion of the lungs. Against this condition in dogs, inhalation of carbon dioxide in oxygen is an effective prophylaxis.
These facts, when they first came to our attention, were both unforeseen and unexplainable. Little stress was laid on them in the publications from