Correlation between rectus femoris muscle cross-sectional area and the severity of airflow limitation in COPD patients

Abstract Peripheral muscle dysfunction is a well-recognized complication of COPD associated with exercise (in)tolerance and worse prognosis. The evaluation of peripheral muscle integrity is an attractive marker in COPD patients. The aim of the study was to identify the correlation between the rectus femoris muscle cross-sectional area (RFCSA) and the severity of airway obstruction in COPD patients using ultrasound. The study enrolled 24 outpatients diagnosed with stable COPD (post-bronchodilator FEV1/FVC < 0.001*. There was a significant negative correlation between RFCSA and age only in cases with very severe airflow limitation. Among COPD patients, there was a significant negative correlation between average RFCSA and mMRC score ( r = − 0.864*, p < 0.001*), but not with FEV1 ( r = 0.165, p = 0.442). No significant correlation between average RFCSA and neither CRP nor heart rate in COPD patients ( r = − 0.169, p = 0.431, r = − 0.285, p = 0.178, respectively. Among COPD, there was a significant positive correlation between RFCSA and QMVC ( r = 0.881*, p < 0.001*). COPD cases showed reduced RFCSA, reduced QMVC, shorter 6MWD distance, and higher mMRC score in comparison to the control group. Ultrasound measurement of RFCSA is an effort-independent, radiation-free method that relates to strength and should be applied as an assessment tool for COPD patients.