The value of nocturnal pulse oximetry, pulmonary function tests and 6 minute walking test in the assessment of disease progression in idiopathic pulmonary fibrosis patients under pirfenidone treatment

Abstract

Introduction Nocturnal pulse oximetry (NPO) has not been widely used in idiopathic pulmonary fibrosis (IPF). Daytime functional tests are common tools of evaluation of the disease. Aims and objectives We investigated whether NPO in association with 6Minute Walking Test (6MWT) and pulmonary function tests (PFTs) could assess the clinical course in IPF. Methods We prospectively investigated consecutive IPF outpatients at the start of Pirfenidone treatment and after 1 year follow-up. Included patients had PFTs, 6MWT and NPO. Results 16 patients of 70.7±6.5 years old, 12 male, 10 with a BMI less than 30, 14 with an index of Gender, Age and Physiology (GAP) I, II. After 1 year of Pirfenidone, there was no significant change in FVC (p=0.82) and DLCO (p=0.08). The Walking Distance decreased (p=0.02). Regarding NPO there was no change in lowest SPO2(p=0.32) nor in desaturation ≤90% for more than 10% of recording time (≤90%≥10%) (p=0.06). The change in desaturation during 6MWT did not correlate with lowest SPO2 (p=0.06) or desaturation ≤90%≥10% (p=0.60). The change in DLCO, did not correlate with lowest SPO2(p=0.53), or desaturation ≤90%≥10% (p=0.65). The change in FVC did not correlate with lowest SPO2 (p=0.48) or desaturation ≤90%≥10% (p=0.06). Conclusions This cohort of IPF patients were stable regarding PFTs but their walking distance in 6MWT was worse after 1 year of follow up. There was a trend towards statistical significance of worsening desaturation of ≤90% for more than ≥10% of recording sleep time. Worsening of desaturation during 6MWT tended to correlate with lowest baseline nocturnal SPO2.