Patients with connective tissue disease-associated pulmonary arterial hypertension (CTD-PAH) showed alterations in pulmonary function that could be detected by a pulmonary function test, a study found.
The authors of the study recently published in Disease Markers identified diffusing capacity of the lung for carbon monoxide (DLCO) as an independent predictive factor for CTD-PAH. Almost all (96%) patients experienced a decrease in DLCO, with most (60%) showing a DLCO of less than 60%.
Moreover, 60% of patients showed decreased forced vital capacity (FVC) and total lung capacity (TLC).
“The reason for lung volume limitation in patients with PAH remains unclear. One explanation is that pulmonary vascular enlargement may have a direct physical effect on the airway, limiting tracheal dilation by mechanical pressure on the airway,” the study authors wrote.
Read more about PAH etiology
Almost all patients (95%) had a forced expiratory volume in 1 second (FEV1)/FVC ratio of greater than 70%. Both FEV1/FVC ratio and TLC improved after treatment for PAH.
In addition, 60% of patients showed decreased maximum expiratory flow at 50% of vital capacity (MEF50), a sensitive marker of small airways. Almost half (42%) presented with a MEF50 of less than 60%, with high-risk patients showing significantly lower MEF50 than low-risk patients.
In contrast to other studies that suggest the use of FVC/DLCO to distinguish PAH from interstitial lung disease, this study found limited use for FVC/DLCO in predicting PAH.
This prospective observational study enrolled 31 patients diagnosed with CTD-PAH (22 patients with systemic lupus erythematosus and 9 patients with systemic sclerosis) at the First Affiliated Hospital of Nanchang University in China. About half (48.4%) of the patients were classified as intermediate risk, while the remaining patients were classified as either low (25.8%) or high (25.8%) risk.
Xiong J, Li J, Huang Y, Yang F, Wu R. The role of pulmonary function test for pulmonary arterial hypertension in patients with connective tissue disease. Dis Markers. 2022;2022:6066291. doi:10.1155/2022/6066291