Mathilde Blanquez-Nadal1, Nicolas Piliero2, Alicia Guillien3, Stéphane Doutreleau4, Muriel Salvat2, Frédéric Thony5, Christophe Pison1, Caroline Augier2, Hélène Bouvaist2, Bernard Aguilaniu1, Bruno Degano6. 1. Service Hospitalier Universitaire Pneumologie Physiologie, Pôle Thorax et Vaisseaux, Centre Hospitalier Universitaire Grenoble Alpes, Grenoble, France; Université Grenoble Alpes, Grenoble, France. 2. Service de Cardiologie, Pôle Thorax et Vaisseaux, Centre Hospitalier Universitaire Grenoble Alpes, Grenoble, France. 3. Service Hospitalier Universitaire Pneumologie Physiologie, Pôle Thorax et Vaisseaux, Centre Hospitalier Universitaire Grenoble Alpes, Grenoble, France; Épidemiologie environnementale appliquée à la reproduction et à la santé respiratoire, INSERM, CNRS, Université Grenoble Alpes, Institut pour l'Avancée des Biosciences (IAB), Grenoble, France. 4. Service Hospitalier Universitaire Pneumologie Physiologie, Pôle Thorax et Vaisseaux, Centre Hospitalier Universitaire Grenoble Alpes, Grenoble, France; Université Grenoble Alpes, Grenoble, France; Laboratoire HP2, INSERM U1042, Université Grenoble Alpes, Grenoble, France. 5. Pole Imagerie, Centre Hospitalier Universitaire Grenoble Alpes, Grenoble, France. 6. Service Hospitalier Universitaire Pneumologie Physiologie, Pôle Thorax et Vaisseaux, Centre Hospitalier Universitaire Grenoble Alpes, Grenoble, France; Université Grenoble Alpes, Grenoble, France; Laboratoire HP2, INSERM U1042, Université Grenoble Alpes, Grenoble, France. Electronic address: bdegano@chu-grenoble.fr.
Abstract
BACKGROUND: Excessive ventilation (V̇E) and abnormal gas exchange during exercise are features of chronic thromboembolic pulmonary hypertension (CTEPH). In selected CTEPH patients, balloon pulmonary angioplasty (BPA) improves symptoms and exercise capacity. How BPA affects exercise hyperventilation and gas exchange is poorly understood. METHODS: In this longitudinal observational study, symptom-limited cardiopulmonary exercise tests and carbon monoxide lung diffusion (DLCO) were performed before and after BPA (interval, mean (SD): 3.1 (2.4) months) in 36 CTEPH patients without significant cardiac and/or pulmonary comorbidities. RESULTS: Peak work rate improved by 20% after BPA whilst V̇E at peak did not change despite improved ventilatory efficiency (lower V̇E with respect to CO2 output [V̇CO2]). At the highest identical work rate pre- and post-BPA (75 (30) watts), V̇E and alveolar-arterial oxygen gradient (P(Ai-a)O2) decreased by 17% and 19% after BPA, respectively. The physiological dead space fraction of tidal volume (VD/VT), calculated from measurements of arterial and mixed expired CO2, decreased by 20%. In the meantime, DLCO did not change. The best correlates of P(Ai-a)O2 measured at peak exercise were physiological VD/VT before BPA and DLCO after BPA. CONCLUSIONS: Ventilatory efficiency, physiological VD/VT, and pulmonary gas exchange improved after BPA. The fact that DLCO did not change suggests that the pulmonary capillary blood volume and probably the true alveolar dead space were unaffected by BPA. The correlation between DLCO measured before BPA and P(Ai-a)O2 measured after BPA suggests that DLCO may provide an easily accessible marker to predict the response to BPA in terms of pulmonary gas exchange.
BACKGROUND: Excessive ventilation (V̇E) and abnormal gas exchange during exercise are features of chronic thromboembolic pulmonary hypertension (CTEPH). In selected CTEPH patients, balloon pulmonary angioplasty (BPA) improves symptoms and exercise capacity. How BPA affects exercise hyperventilation and gas exchange is poorly understood. METHODS: In this longitudinal observational study, symptom-limited cardiopulmonary exercise tests and carbon monoxide lung diffusion (DLCO) were performed before and after BPA (interval, mean (SD): 3.1 (2.4) months) in 36 CTEPH patients without significant cardiac and/or pulmonary comorbidities. RESULTS: Peak work rate improved by 20% after BPA whilst V̇E at peak did not change despite improved ventilatory efficiency (lower V̇E with respect to CO2 output [V̇CO2]). At the highest identical work rate pre- and post-BPA (75 (30) watts), V̇E and alveolar-arterial oxygen gradient (P(Ai-a)O2) decreased by 17% and 19% after BPA, respectively. The physiological dead space fraction of tidal volume (VD/VT), calculated from measurements of arterial and mixed expired CO2, decreased by 20%. In the meantime, DLCO did not change. The best correlates of P(Ai-a)O2 measured at peak exercise were physiological VD/VT before BPA and DLCO after BPA. CONCLUSIONS: Ventilatory efficiency, physiological VD/VT, and pulmonary gas exchange improved after BPA. The fact that DLCO did not change suggests that the pulmonary capillary blood volume and probably the true alveolar dead space were unaffected by BPA. The correlation between DLCO measured before BPA and P(Ai-a)O2 measured after BPA suggests that DLCO may provide an easily accessible marker to predict the response to BPA in terms of pulmonary gas exchange.