The Current Role of Cardiopulmonary Exercise Test in the Diagnosis and Management of Pulmonary Hypertension

Figures

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  Figure 1. The minute ventilation (VE)/carbon dioxide production (VCO2) relationship slope in two pulmonary arterial hypertension patients. In (a), the physiological behavior of ventilation during exercise is preserved in spite of hyperventilation, such that two slopes can be recognized around the respiratory compensation (RC) point (slope 1 (S1) = 40.4 and slope 2 (S2) = 55.1). In (b), a single slope characterizes the VE/VCO2 relationship. Reproduced with permission of the © ERS 2023: European Respiratory Review 27 (148), 170134; DOI: 10.1183/16000617.0134-2017 Published 2 May 2018 [28].

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  Figure 2. A schematic representation of the VE/VCO2 slope in a ramp incremental exercise test. Panel (a), normal subject—Lower line: alveolar ventilation (VE alv) vs. VCO2 up to the isocapnic buffering period. Upper line: total ventilation (VE alv + naturally-occurring dead space VE DS natural) vs. VCO2. Dotted lines: extrapolation to the Y axis (VE intercepts) for both VE alv and total ventilation. Panel (b), normal subject with added external dead space (DS)—In addition to the lines depicted in panel (a), highest line: total ventilation plus the added DS (VE alv + VE DS natural + VE DS added) vs. VCO2. Panel (c), patient with moderate-to severe COPD—VE alv vs. VCO2 relationship as in panels (a,b). Panel (d), patient with moderate heart failure—VE alv vs. VCO2 as in panels (a–c). VE DS shows a moderate increase resulting in a slight slope increase with an extrapolation to the Y axis (intercept) close to 0. Panel (e), patient with severe heart failure or pulmonary arterial hypertension—VE alv vs. VCO2 relationship as in upper panels. VE DS increases during exercise. The extrapolation to the Y axis (intercept) of total ventilation now has a negative value (From Apostolo A et al., Int. J.…

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  Figure 3. Scatterplot of the VE/VCO2 slope versus peak PETCO2 (from Pezzuto et al., Pulm. Circul. 2022, 12, e12044 [60], with permission). PETCO2: end-tidal carbon dioxide pressure; VE/VCO2 slope: ventilation to carbon dioxide production slope.