Only a few small studies have evaluated the relationship between iPAH, expiratory flow limitation, and exercise dyspnea. While not all patients with iPAH demonstrate airway involvement, those who demonstrate dynamic hyperinflation (DH), defined as a variable and temporary increase in end-expiratory lung volume, report increased dyspnea with exertion on maximal testing. There is a continued need for adjuvant therapy in iPAH, and bronchodilators have the potential to ameliorate dyspnea during exercise, which could lead to improved quality of life in this disabling condition. This study will investigate the presence of airway involvement in this population as measured by dynamic hyperinflation, and if there is any improvement in function with the use of inhaled albuterol.
