Faculty Collaboration Database

Distinguishing exercise intolerance in early-stage pulmonary hypertension with invasive exercise hemodynamics: Rest V_E /VCO₂ and ETCO₂ identify pulmonary vascular disease. Clin Cardiol 2022 Jul;45(7):742-751

Date

04/15/2022

Pubmed ID

35419844

Pubmed Central ID

PMC9286332

DOI

10.1002/clc.23831

Scopus ID

2-s2.0-85129078510 (requires institutional sign-in at Scopus site)   16 Citations

Abstract

BACKGROUND: Among subjects with exercise intolerance and suspected early-stage pulmonary hypertension (PH), early identification of pulmonary vascular disease (PVD) with noninvasive methods is essential for prompt PH management.

HYPOTHESIS: Rest gas exchange parameters (minute ventilation to carbon dioxide production ratio: V_E /VCO₂ and end-tidal carbon dioxide: ETCO₂ ) can identify PVD in early-stage PH.

METHODS: We conducted a retrospective review of 55 subjects with early-stage PH (per echocardiogram), undergoing invasive exercise hemodynamics with cardiopulmonary exercise test to distinguish exercise intolerance mechanisms. Based on the rest and exercise hemodynamics, three distinct phenotypes were defined: (1) PVD, (2) pulmonary venous hypertension, and (3) noncardiac dyspnea (no rest or exercise PH). For all tests, *p < .05 was considered statistically significant.

RESULTS: The mean age was 63.3 ± 13.4 years (53% female). In the overall cohort, higher rest V_E /VCO₂ and lower rest ETCO₂ (mm Hg) correlated with high rest and exercise pulmonary vascular resistance (PVR) (r ~ 0.5-0.6*). On receiver-operating characteristic analysis to predict PVD (vs. non-PVD) subjects with noninvasive metrics, area under the curve for pulmonary artery systolic pressure (echocardiogram) = 0.53, rest V_E /VCO₂  = 0.70* and ETCO₂  = 0.73*. Based on this, optimal thresholds of rest V_E /VCO₂  > 40 mm Hg and rest ETCO₂  < 30 mm Hg were applied to the overall cohort. Subjects with both abnormal gas exchange parameters (n = 12, vs. both normal parameters, n = 19) had an exercise PVR 5.2 ± 2.6* (vs. 1.9 ± 1.2), mPAP/CO slope with exercise 10.2 ± 6.0* (vs. 2.9 ± 2.0), and none included subjects from the noncardiac dyspnea group.

CONCLUSIONS: In a broad cohort of subjects with suspected early-stage PH, referred for invasive exercise testing to distinguish mechanisms of exercise intolerance, rest gas exchange parameters (V_E /VCO₂  > 40 mm Hg and ETCO₂  < 30 mm Hg) identify PVD.

Author List

Raza F, Dharmavaram N, Hess T, Dhingra R, Runo J, Chybowski A, Kozitza C, Batra S, Horn EM, Chesler N, Eldridge M

Author

Ravi Dhingra MBBS Professor in the Medicine department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Carbon Dioxide
Dyspnea
Exercise Test
Female
Hemodynamics
Humans
Hypertension, Pulmonary
Male
Oxygen Consumption