Background: Patients with pulmonary arterial hypertension often present with a mild obstructive lung pattern, however, the functional consequences are not known.
Methods: We analysed flow volume loops during exercise in 61 patients with precapillary pulmonary hypertension (PH) (age 55 ± 14 years) in comparison with 21 patients with COPD (60 ± 12 years), 39 patients with pulmonary fibrosis (58 ± 11 years) and 38 healthy controls (HC) (39 ± 15 years). Inspiratory capacity (IC) was measured at rest, and during maximum exercise (max).
Results: HC exhibited a stable IC of 3.0 ± 0.9 l at rest, and at max. A reduction in IC of 2.6 ± 0.8 l at rest to 2.0 ± 0.7 l at max was observed in patients with COPD. Patients with PH exhibited a significant reduction in IC from 2.3 ± 0.6 l at rest to 2.1 ± 0.6 l at max, while patients with pulmonary fibrosis exhibited a stable IC of 1.8 ± 0.6 at rest and 1.7 ± 0.6 l at max. In patients with PH, a weak negative correlation was drawn between the change in IC (%) and peak VO2 (r = -0.29, p = 0.01), as well as with PVR (r = -0.27, p = 0.02).
Conclusion: Patients with PH demonstrate a characteristic change in IC during exercise, which might contribute to impaired exercise tolerance.
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