THE RELATION BETWEEN CARDIAC OUTPUT AND BODY SIZE

Abstract

Comparison was made between height, weight, and body surface area on the one hand and cardiac output measured by dye-dilution method, stroke volume, and peripheral vascular resistance on the other. Seventy-seven subjects were studied ranging in body size from 0[center dot]2-2[center dot]0 m2 bsa [square meter of body surface area.] Correlation between cardiac output and stroke volume with height, weight, and body surface area was high. Linear regression equations were calculated which related cardiac output and stroke volume respectively to body surface area. The mean cardiac index was 3[center dot]38 1/min/m2bsa and the mean stroke index was 42[center dot]5 ml/beat/ m2bsa. The data supported the validity of these indices as a means of eliminating the influence of body size from the hemodynamic data. The influence of age on the hemodynamic parameters indicated that the cardiac index was slightly higher in young children whereas the stroke index was somewhat lower in younger age-groups. Both blood pressure and systemic resistance index showed an increase up to age 15 years.