RT Journal Article SR Electronic T1 Ultrasound diaphragm activity in patients with cystic fibrosis: relationship to disease severity and peripheral muscle strength JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP 4346 DO 10.1183/13993003.congress-2020.4346 VO 56 IS suppl 64 A1 Anne-Catherine Maynard A1 François Tremblay A1 Bruno-Pierre Dubé YR 2020 UL http://erj.ersjournals.com/content/56/suppl_64/4346.abstract AB Rationale: Cystic fibrosis (CF) is associated with changes in respiratory and peripheral skeletal muscles, but their relationship is not fully understood. Ultrasonography (US) can provide an evaluation of diaphragm activity, but data in CF patients is lacking. This study aimed to compare US-derived diaphragm function to usual markers of disease severity and to peripheral muscle strength in this population.Methods: Stable CF patients were prospectively recruited. US Diaphragm activity was evaluated using TF%max, defined as [thickening fraction during tidal breathing / thickening fraction during maximal inspiration]. Exacerbation rate, dyspnea level (mMRC scale), lung function testing, C-reactive protein (CRP), transthyretin (TT), handgrip strength (HS) and body composition were measured and compared to TF%max.Results: 22 patients were included (16 males, mean FEV1 56±29%. Mean TF%max was 28±20%, was inversely related to FEV1 (rho=0.73, p<0.01) and was significantly related to dyspnea level (b=0.60; p=0.003), 1-year exacerbation rate (b=0.45, p=0.03) and was significantly lower in patients with mMRC<2 compared to those with higher score (22±18 vs 40±17%, p=0.03). TF%max was correlated to CRP level (b=0.57, p<0.01) but not to TT, fat-free mass or HS (all p=NS).Conclusion: In patients with CF, TF%max is related to clinical severity and could provide a novel tool to assess disease burden. No association was found with markers of peripheral muscle status and strength, suggesting that the respiratory and peripheral involvement in CF probably have different determinants. Additional studies are required to further explore this relationship.FootnotesCite this article as: European Respiratory Journal 2020; 56: Suppl. 64, 4346.This abstract was presented at the 2020 ERS International Congress, in session “Respiratory viruses in the "pre COVID-19" era”.This is an ERS International Congress abstract. No full-text version is available. Further material to accompany this abstract may be available at www.ers-education.org (ERS member access only).