Relation Between Basal Metabolism and Minute Volume of Circulation

Abstract

One of the main functions of the circulation is the transportation of oxygen. A priori, reasoning would indicate that there is a close correlation between oxygen consumption and rate of oxygen transportation. Grollman 1 expressed this supposed relationship in his “cardiac index” which correlates minute volume at rest with square meters of body surface. He defines “cardiac index” as the minute volume per square meter of body surface. In a large series of determinations on normal individuals, he found that his “cardiac index” was 2.2 liters per square meter of body surface. The standard deviation in this series of determinations was 0.3. Grollman's cardiac index does not take into account the variability in the basal metabolic rate of normals. As we know, this rate varies —15 to +15 in any large series of normal cases. Believing that a better cardiac index could be obtained by taking into consideration the basal metabolic rate, we have constructed a formula which fits the determination somewhat better than the Grollman index. Our formula which was developed from our own data is minute volume = 2.2A (100 + BMR/100) where A = the body surface in square meters and BMR is the basal metabolic rate expressed in the usual way. In other words, we would define cardiac index as the minute volume per square meter body surface at 0% basal metabolic rate. When this formula is used to calculate the minute volume, it is found that the determined minute volume will differ only very slightly from the calculated minute volume. In our work we did not confine ourselves solely to normal persons. We used not only a large number of normals with basal metabolic rates varying from −28 to +12 but also determinations on cases of hyperthyroidism, on cases in which artificial fever had increased the basal metabolic rate during the fever, on myxedema cases before and after treatment, on patients whose basal metabolic rate had been changed by reduction in diet, and on cases, in which basal metabolic rate had been increased following adrenalin injections, etc. (Table I.)