Continuous breathing circuit flow and tracheal tube cuff leak: Sources of error during pediatric indirect calorimetry

Abstract

An indirect calorimeter in which measurement of Vo2 is based on internal constant flow rather than spirometry can be used to accurately measure Vo2 from a continuous-flow breathing circuit, if the total circuit flow is less than the internal flow. This limitation may restrict the use of continuous flow to a level below the subject's peak inspiratory flow. The accuracy of indirect calorimetry cannot be guaranteed for any amount of tracheal tube cuff leak. (Crit Care Med 1992; 20:1335–1340)