DETERMINATION OF BASAL RATE OF OXYGEN CONSUMPTION BY OPEN AND CLOSED-CIRCUIT METHODS

Abstract

INTRODUCTION FOR many years the routine clinical measurement of basal metabolic rate (BMR) at this institution has been performed with the opencircuit method, as used to establish the Mayo Foundation Standards (1). However, newer laboratory methods for evaluating thyroid function, such as measurement of the protein-bound iodine concentration in serum and measurements utilizing radioiodine, now provide additional information. In evaluating the relative utility and complexity of the various procedures, the question arose as to the degree of accuracy provided by the “simpler” closed-circuit method for measuring oxygen consumption that is in almost universal clinical usage. The limitations of available data, as noted later in this paper, made it advisable to compare the results obtained by both open and closed-circuit methods in a series of patients having routine tests. In some cases the errors of the closed-circuit method were of clinical importance. The sources of these errors, including some that have not been generally recognized, are discussed. This presentation is concerned with the measurement of the rate of oxygen consumption, and not with the question of the metabolic standards with which it is compared (2).