Transcutaneous PCO₂ for Exercise Gas Exchange Efficiency in Chronic Obstructive Pulmonary Disease

Gas exchange inefficiency and dynamic hyperinflation contributes to exercise limitation in chronic obstructive pulmonary disease (COPD). It is also characterized by an elevated fraction of physiological dead space (VD/VT). Noninvasive methods for accurate VD/VT assessment during patients are lacking. The current study sought compare transcutaneous PCO2 (TcPCO2) with the gold standard—arterial (PaCO2)—and other available (end tidal CO2 Jones equation) estimating incremental COPD. Ten COPD completed a symptom limited cycle exercise. TcPCO2 was measured heated electrode on ear-lobe. Radial artery blood collected at rest, unloaded cycling (UL) every minute recovery. Ventilation gas were breath-by-breath. Bland-Altman analysis examined agreement calculated using PaCO2, TcPCO2, end-tidal (PETCO2) estimated PaCO2 equation (PaCO2-Jones). Lin’s Concordance Correlation Coefficient (CCC) assessed. 114 measurements obtained from 10 subjects. bias between 0.86 mmHg upper lower limit ranging ?2.28 3.99 mmHg. rest r2=0.907 (p < 0.001; CCC = 0.941) vs. r2=0.958 0.0001; 0.967). PaCO2-Jones PETCO2 r2=0.755, 0.755, 0.832, 0.718) calculation (r2=0.793, 0.610; p 0.760, 0.448), respectively. results support accuracy reflect calculate exercise, but not recovery, patients, enabling improved noninvasive testing.