Abstract
Patients with pulmonary arterial hypertension (PAH) may exhibit reduced expiratory flows at low lung volumes, which could promote exercise-induced dynamic hyperinflation (DH). This study aimed to examine the impact of a potential exercise-related DH on the intensity of dyspnoea in patients with PAH undergoing symptom-limited incremental cardiopulmonary cycle exercise testing (CPET).
25 young (aged mean±sd 38±12 yrs) nonsmoking PAH patients with no evidence of spirometric obstruction and 10 age-matched nonsmoking healthy subjects performed CPET to the limit of tolerance. Ventilatory pattern, operating lung volumes (derived from inspiratory capacity (IC) measurements) and dyspnoea intensity (Borg scale) were assessed throughout CPET.
IC decreased (i.e. DH) progressively throughout CPET in PAH patients (average 0.15 L), whereas it increased in all the healthy subjects (0.45 L). Among PAH patients, 15 (60%) exhibited a decrease in IC throughout exercise (average 0.50 L), whereas in the remaining 10 (40%) patients IC increased (average 0.36 L). Dyspnoea intensity and ventilation were greater in PAH patients than in controls at any stage of CPET, whereas inspiratory reserve volume was lower.
We conclude that DH-induced mechanical constraints and excessive ventilatory demand occurred in these young nonsmoking PAH patients with no spirometric obstruction and was associated with exertional dyspnoea.
Footnotes
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Support Statement
P. Laveneziana was supported by: 1) the Seventh Framework Programme of the European Union, Support for training and career development of researchers (Marie Curie), International Re-integration Grants (IRG), FP7-PEOPLE-2010-RG, grant number PIRG07-GA-2010-268396-EDPAH; and 2) PFIZER Investigator-Initiated Research (IIR), Grant number WS 942458.
Statement of Interest
Statements of interest for P. Laveneziana, O. Sitbon, G. Simonneau, M. Humbert and T. Similowski can be found at www.erj.ersjournals.com/site/misc/statements.xhtml
- Received December 20, 2011.
- Accepted June 9, 2012.
- ©ERS 2013