Diaphragmatic dysfunction evaluated by ultrasound correlates with dyspnea, exercise and quality of life in interstitial lung disease

Background: respiratory muscle dysfunction may contribute to exercise limitation in interstitial lung disease (ILD). Diaphragmatic dysfunction was demonstrated by ultrasound (US) in ILD patients. However, diaphragmatic dysfunction described on US was not correlated with functional parameters. Aims: to correlate in ILD patients, diaphragmatic mobility and thickness with rest dyspnea, performance on 6-minute-walk test (6MWT) and quality of life (QOL). Methods: 28 controls and 24 ILD patients performed spirometry and US of diaphragm to evaluate deep breathing (DB) mobility and thickness fraction (TF). Only patients performed 6MWT and reported MRC dyspnea and QOL on St. George9s Respiratory Questionnaire (SGRQ). Results: compared to controls, ILD patients had a lower DB diaphragmatic mobility and a decreased TF In ILD patients, diaphragmatic mobility and thickness were not correlated with ventilatory muscle strength. However, DB mobility and TF strongly correlated with spirometry, MRC, and QOL on SGRQ Conclusions: In ILD patients, DB diaphragmatic mobility and TF are reduced. This reduction is strongly correlated with pulmonary restriction, rest dyspnea, poor healthy related QOL, exercise dessaturation and tachycardia.