Accurate measurement of functional residual capacity and oxygen consumption of patients on mechanical ventilation.

We developed an apparatus and technique for the simultaneous measurement of functional residual capacity and oxygen uptake (VO2) for use in intensive care unit (ICU) patients. The accuracy of the functional residual capacity measurement was proven using an in vitro lung model and the reproducibility of this measurement was established by use in ICU patients. We tested the accuracy of the VO2 measurement in comparison with two other methods in common use among ICU patients and our method proved accurate. We conclude that this technique for measurement of functional residual capacity and VO2 is highly accurate and easily applied to patients on any mode of mechanical ventilation.