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. RESULTS: 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 ((V)Over dotO(2peak) = 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.