Utility of ultrasound assessment of diaphragmatic function before and after pulmonary rehabilitation in COPD patients

Claudia Crimi,1 Enrico Heffler,2 Teresa Augelletti,2 Raffaele Campisi,1 Alberto Noto,3 Carlo Vancheri,4 Nunzio Crimi2 1Respiratory Medicine Unit, AOU “Policlinico-Vittorio Emanuele”, Catania, Italy; 2Respiratory Medicine Unit, Department of Clinical and Experimental Medicine, AOU “Policlinico-Vittorio Emanuele”, University of Catania, Catania, Italy; 3Anesthesia and Intensive Care Unit, AOU Policinico “G. Martino”, Messina, Italy; 4Regional Referral Centre for Rare Lung Diseases, A.O.U. “Policlinico-Vittorio Emanuele”, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy Background: Pulmonary rehabilitation (PR) may improve respiratory symptoms and skeletal muscle strength in patients with COPD. We aimed to evaluate changes in ultrasound (US) measurements of diaphragmatic mobility and thickness after PR in COPD patients and to test its correlation with PR outcomes.Methods: Twenty-five COPD patients were enrolled and underwent a diaphragm US assessment before and after a 12-week PR program.Results: We found a correlation between the intraindividual percentage of change in the diaphragmatic length of zone of apposition at functional residual capacity (ΔLzapp%) and the change in 6-minute walking distance (6MWD) after PR (rho=0.49, P=0.02). ΔLzapp% was significantly higher in patients with improved 6MWD and COPD Assessment Test (CAT) score (mean rank=12.03±2.57 vs 6.88±4.37; P=0.02). A ΔLzapp% of ≥10% was able to discriminate among patients with improved 6MWD, with a sensitivity of 83% and a specificity of 74%. The area under the receiver operating characteristic curve for ΔLzapp% was 0.83. A cutoff value of ≥9% of ΔLzapp% had a positive predictive value in discriminating a reduction in ≥2 points of CAT score after PR, with a sensitivity and a specificity of 80% and 62%, respectively.Conclusion: Diaphragm US assessment represents a useful prognostic marker of PR outcomes in COPD patients. Keywords: diaphragm ultrasound, COPD, pulmonary rehabilitation