The term "croup" is used to designate a state of obstruction to the entrance of air into the lungs as the result of an inflammatory process either in the larynx alone or extending to the lower respiratory tract. It is characterized by inspiratory stridor, hoarseness or aphonia and cyanosis or pallor, accompanied by suprasternal, epigastric and intercostal retractions.
There are two main types, diphtheritic and nondiphtheritic.
Formerly most attention was focused on the diphtheritic type, since that type was the principal cause of obstruction. Before extensive use of toxin-antitoxin, 60 per cent of the cases of croup were of the diphtheritic type, but in the past year the incidence of diphtheritic croup fell to only 7 per cent. Of 450 cases of croup encountered at the Kingston Avenue Hospital in 1929, 316 were of the diphtheritic and 134 of the nondiphtheritic type. In the year beginning April 1, 1939 and