In asthma the following clinical observations have been made :
Low pulse pressure in those cases uncomplicated by arteriosclerosis, probably due to diminished systolic volume.
Loud pulmonic second sound pointing towards increased resistance in the lesser circulation.
Polycythemia, possibly a teleologic phenomenon designed to compensate for a lessened minute volume output from the left ventricle.
Enlarged veins in the neck and cyanosis suggesting a certain amount of general venous stasis.
These clinical facts led us to suspect that circulatory disturbances might account in large part for the conditions associated with obstructed expiration. On account of the lack of adequate clinical material, we decided to study this subject in the experimental animal. Dogs were used.
The animals received a preliminary injection of 0.16 c.c. of a 2 per cent. solution of morphin per kilogram of body weight. Full anesthesia was produced by the
FRIEDMAN ED, JACKSON HC. THE CARBON DIOXID CONTENT OF BLOOD AND OF ALVEOLAR AIR IN OBSTRUCTED EXPIRATION. Arch Intern Med (Chic). 1917;XIX(5_I):767–776. doi:10.1001/archinte.1917.00080240086006