Abstract 15497: Clinical Significance of the Overshoot Phenomena of Respiratory Gas Indices During Recovery After Maximal Exercise Testing in Cardiac Patients
Background: Overshoot phenomena of the gas exchange ratio (R:VCO2/VO2), ventilatory equivalent for O2 (VE/VO2), and end-tidal O2 pressure (PETO2) are commonly observed during recovery from maximal cardiopulmonary exercise testing (CPX). We investigated the clinical significance of the overshoots of these indices by comparing their magnitudes between healthy subjects and cardiac patients.
Methods: In total, 372 subjects (79 healthy subjects and 293 cardiac patients) who underwent CPX and achieved peak R ≥ 1.10 were enrolled. We evaluated and calculated the presence and magnitude of the overshoot phenomena of R, VE/VO2, and PETO2.
Results: The overshoot phenomena of R, VE/VO2, and PETO2 were observed in almost all the subjects. The magnitudes of the R (26.5±12.0 vs 29.9±10.2%, p=0.012), VE/VO2 (61.2±27.8 vs 78.8±29.5%, p<0.001), and PETO2 (7.9±3.9 vs 10.2±4.3%, p<0.001) overshoots were significantly lower in cardiac patients than in healthy subjects. In cardiac patients, the magnitude of the PETO2 overshoot showed significant positive correlations with the peak O2 uptake (VO2) (r=0.42, p<0.001), anaerobic threshold (r=0.42, p<0.001), and ratio of the increase in VO2 to the increase in the work rate (r=0.32, p<0.001), and a negative correlation with the slope of the increase in ventilation versus the increase in CO2 output (r=-0.57, p<0.001). The magnitudes of the R and VE/VO2 overshoots showed the same patterns of significant correlation with the CPX indices.
Conclusions: We concluded that the overshoots of R, VE/VO2, and PETO2 during recovery from maximal exercise reflect the natural cardiopulmonary adaptation after exercise and are more prominent in subjects with better cardiopulmonary function.
Author Disclosures: O. Nagayama: None. A. Koike: None. Y. Takayanagi: None. A. Nagamine: None. Q. Ru Jie: None. J. Kato: None. T. Himi: None. Y. Kato: None. A. Sato: None. T. Yamashita: None. K. Aonuma: None.
- © 2016 by American Heart Association, Inc.