Method for continuous measurement of carbon dioxide output

Abstract

An open-circut flow-through technique for the continous measurement of carbon dioxide output in man has been described. A stream of room air is drawn past the subject who respires freely from it. The difference in the concentration of carbon dioxide between room air from which the subject inspires and the expired gas/room air mixture is measured and expressed as a voltage. This voltage is amplified by a factor proportional to the rate of flow of room air to yield a continous measurement of carbon dioxide output. This technique has no systematic error and a random error (95% tolerance limits) of +/-3.4, +/-1.7, and +/-1.4% at mean carbon dioxide outputs of 254, 846, and 1,906 ml/min, respectively.