(92f) Dynamic Measurement of Endogenous Acetone in Exhaled Breath As a Non-Invasive Alternative to Obtain Diffusing Capacity of the Lung

Diffusing Capacity of the Lung for Carbon Monoxide (DLCO) is a well-established procedure for measuring the efficiency of pulmonary gas exchange to diagnose pulmonary diseases and particularly Idiopathic pulmonary fibrosis. The method uses a tracer gas such a helium to obtain lung volume and an exogeneous source of carbon monoxide to provide a well-defined concentration gradient. Ultimately, one obtains the mass transfer coefficient of alveolar lung tissue and associated resistances. In this work, we discuss development of a sensor that uses of endogenous acetone as a non-invasive and more convenient alternative to DLCO.

Given that a typical breath exhalation can be sustained no longer than ~40 s, any exhaled breath analysis sensing method requires time resolution on the order of 1 s to be able to deconvolute the time-scales of the mass transport processes involved. Existing portable detection methods for endogenous volatile organic compounds (VOCs) such as acetone rarely achieve such time resolution and rely on ex-situ analysis of a collected breath sample. Furthermore, water in exhaled breath presents a significant interference for typical potentiometric or optical sensing approaches. We have previously shown that immobilized organic reagents in perflurosulfonic acid membranes can undergo a rapid water-resistant color change by reacting with acetone in exhaled breath. Our recent investigations have disclosed how such behavior is enabled by differing transport pathways in the membrane for acetone and water. We will here present application of this optical sensing approach in small scale clinical investigations that reveal the alveolar mass transport resistance to acetone transport. Comparison to DLCO results will be discussed.