Defining reference intervals for submaximal cardiopulmonary exercise testing-derived gas-exchange derived pulmonary...

Area of Science:

• Cardiopulmonary Physiology
• Exercise Science
• Medical Diagnostics

Background:

• Pulmonary arterial capacitance assessment is crucial, especially in older adults.
• Gas-exchange derived pulmonary capacitance (GXCAP) offers a non-invasive method via submaximal cardiopulmonary exercise testing (CPET).
• Existing reference intervals for GXCAP in older adults are lacking.

Purpose of the Study:

• To establish sex-specific reference intervals for GXCAP metrics in adults aged 60 years and older.
• To evaluate the utility of the refineR algorithm for generating clinically interpretable reference intervals.
• To explore the associations of age and sex with GXCAP parameters.

Main Methods:

• Secondary analysis of 207 adults (≥60 years) from a clinical device trial.
• Submaximal CPET using the Shape II system to measure peak GXCAP, GXCAP-time slope, and GXCAP-VO2 slope.
• Calculation of empirical and indirect (refineR algorithm) reference intervals; examination of age and sex associations.

Main Results:

• Males exhibited higher peak GXCAP and steeper slopes compared to females.
• Age showed a modest inverse association with peak GXCAP and GXCAP-time slope.
• The refineR algorithm yielded narrower, physiologically plausible reference intervals compared to empirical ones.

Conclusions:

• GXCAP metrics demonstrate significant sex differences in older adults undergoing preoperative evaluation.
• RefineR-based indirect reference intervals offer stable and clinically relevant ranges for GXCAP in submaximal CPET.
• Introduced GXCAP derivatives (slopes) may provide additional benefits for submaximal CPET assessments.