Interpretation of respiratory tract histology in cot deaths.

The degree of inflammation in the trachea, bronchi, and lungs of 139 cot deaths has been analysed and each case allocated to one of four groups. In group I the changes were considered to be serious enough to have caused death, while group II cases showed similar abnormalities but of a less severe nature, and in this group there was some doubt as to whether they were a significant cause of death. Group III lesions were very minor in type and were not considered to be serious enough to have resulted in the death of the child. There was a good correlation between the degree of inflammation in the respiratory tract, and whether or not bacteria of any type were grown. The great majority of the bacterial pathogens were isolated from the first two groups. Respiratory viruses were isolated from three of the four cases of acute bronchiolitis included in group I, and also from a group II case which showed considerable bronchiolar inflammation. One-third of the cases with minor inflammation in the lung parenchyma (group III) showed some evidence of recent virus infection.