[Peripheral small airway dysfunction differences between idiopathic pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension].

Objective: To investigate the peripheral small airway dysfunction differences between idiopathic pulmonary arterial hypertension (IPAH) and chronic thromboembolic pulmonary hypertension (CTEPH). Methods: Impulse oscillmetory system testing (IOS) and pulmonary function testing (PFT) were performed in IPAH and CTEPH patients and 30 healthy control group. We also carried out a subgroup analysis depending on their medical history of airway diseases. Results: We included 42 IPAH and 47 CTEPH patients (with or without airways disease: 8 vs . 34 and 17 vs . 34, respectively). Compared with CTEPH patients, IPAH patients were younger but had more serious pulmonary vessel resistance and mean pulmonary arterial resistance. Compared with IPAH patients, CTEPH patients had significant impaired peripheral small airway dysfunction with decreased of MEF(50) (% pred), MMEF(75/25) evaluated by PFT and R5-R20, Δ R5-R20 and AX measured by IOS [10.6(2.0, 33.0) vs . 2.5(-5.0, 16.5); 22.1(14.0, 32.6) vs . 15.5 (7.0, 23.2); 7.64(4, 18.6) vs . 6(3, 11) respectively, all P< 0.05]. Subgroup analysis revealed there were no significant peripheral small dysfunction differences in IPAH patients with or without airway diseases. CTEPH patients had a higher proportion of airway diseases and more serious peripheral dysfunction than IPAH patients with airway diseases. Compared with control healthy group, peripheral airway dysfunction was more obvious even in IPAH and CTEPH patients without airway diseases. Conclusion: Compared with IPAH, CTEPH patients were older, but had better hemodynamics and a higher proportion of airway diseases. The peripheral airway dysfunction were more serious in CTEPH patients without airway diseases than IPAH patients without airway diseases and healthy controls group.