Abstract
Changes in the carbon dioxide combining capacity of the blood in normal individuals following vigorous exercise have been reported by a number of investigators. These changes consisted chiefly of a decrease in this constituent. Barr, Himwich, and Green1 found that easy muscular exercise may be performed with little or no change, but that with heavier work the degree of change in carbon dioxide combining capacity increases rapidly with each small increase in the amount of work.
The purpose of this investigation was to determine whether or not similar changes in the carbon dioxide combining capacity occur in individuals with organic heart disease after performing a definite amount of work. The majority of the cases studied were children between the ages of 8 and 16 years, with organic heart disease caused by the infection of rheumatic fever. We also made observations on two normal individuals, and one case of congenital heart disease. The exercise consisted of climbing thirty feet of stairs in forty seconds. In a number of milder cases, the effect of climbing sixty feet was studied. The patients were ambulatory, but varied in their ability to carry on physical activity. The cases were classified according to the classification adopted by the American Heart Association: Class I. Organic—able to carry on habitual physical activity. Class II. Organic—able to carry on: A. Slightly diminished physical activity; B. Greatly diminished physical activity. Class III. Organic—unequal to any physical activity. Class E. Possible—having doubtful murmurs, mainly accidental, possibly organic. Class F. Potential—having a predisposing history.
Blood was taken from a cubital vein without pressure after the patients had rested at least one half hour, and again approximately three minutes after the exercise was completed. The carbon dioxide combining capacity was determined immediately by means of Van Slyke's apparatus.
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