Pulmonary function testing in patients with pulmonary arterial hypertension.

Area of Science:

• Pulmonary Medicine
• Cardiology
• Respiratory Physiology

Background:

• Peripheral airway obstruction is known in idiopathic pulmonary arterial hypertension (IPAH).
• Pulmonary function tests (PFTs) are less studied in pulmonary arterial hypertension associated with congenital heart disease (CHD-PAH) and connective tissue disease (CTD-PAH).

Purpose of the Study:

• To investigate pulmonary function test abnormalities in various subtypes of pulmonary arterial hypertension (PAH).
• To compare PFTs across idiopathic PAH (IPAH), CHD-PAH, and CTD-PAH patient groups.

Main Methods:

• A multicenter prospective study involving 190 PAH patients in China.
• Evaluation of comprehensive pulmonary function tests, including spirometry and diffusion capacity.
• Comparison of PAH patients with control groups.

Main Results:

• PAH patients exhibited decreased airflow measures (VC, FVC, FEV1, FEV1/FVC, MEF50) and reduced single-breath diffusion capacity for carbon monoxide (DLCO).
• Expiratory flow-volume curves showed characteristic reductions and a curvilinear pattern in PAH.
• Similar PFT abnormalities were noted across IPAH, CHD-PAH, and CTD-PAH subgroups, with CTD-PAH patients having more frequent abnormal DLCO.

Conclusions:

• Airway obstruction is a prevalent finding in IPAH, CHD-PAH, and CTD-PAH.
• CTD-PAH patients demonstrate a lower DLCO compared to other PAH subtypes.
• Pulmonary function indices did not strongly correlate with hemodynamic, serum, or exercise capacity parameters.