Physiological profile and limitations in exercise in idiopathic pulmonary fibrosis

Purpose: This study aimed to describe the physiological profile and limiting factors during exercise among patients with idiopathic pulmonary fibrosis. Methods: A descriptive study involving 34 patients with idiopathic pulmonary fibrosis (22 men) aged 68 ± 8 years was conducted. All patients completed a pulmonary function test, cardiopulmonary exercise test, Doppler echocardiography, 6-minute walk test, and modified Medical Research Council dyspnea evaluation. Result: Approximately 38%of patients (range, 15%-71%) presented with coexisting comorbidities including pulmonary hypertension and emphysema. Modified Medical Research Council grades 0-2 and 3-4 were assigned to 68%and 32%of patients, respectively. Median values for forced vital capacity and diffusion capacity for carbon monoxide percent (%) predicted were 68 (95%CI, 63-76) and 51 (95%CI, 46-55), respectively. Left ventricular systolic function was normal. Aerobic capacity (VO_{2 peak}=13.4 mL/kg/min [95%CI, 12.6-14.9]; 62%predicted [95%CI, 56-67]) was moderately reduced with the presence of abnormalities in pulmonary gas exchange and desaturation, circulatory impairments, inefficient ventilation, and skeletal muscle dysfunction. Functional capacity was normal (6-minute walk test distance=505 m [95%CI, 435-522]; 99%predicted [95%CI, 91-108]). Conclusions: The physiological profile demonstrated the presence of comorbidities in approximately 38%of patients with idiopathic pulmonary fibrosis and a moderate level of dyspnea. Resting cardiopulmonary function showed moderate pulmonary restriction and severe impairments in diffusion capacity with normal left ventricular systolic function. Multifactorial limitations for a moderately diminished aerobic capacity were revealed during the cardiopulmonary exercise test, although functional capacity was normal. These results emphasize the significance of a meticulous evaluation, including the cardiopulmonary exercise test for an accurate exercise tolerance evaluation, to aid in the diagnosis and prognosis and for developing effective targeted treatments.