Ultrasonographic assessment of skeletal muscle mass and diaphragm function in patients with chronic obstructive pulmonary disease: A case–control study

BACKGROUND: Although muscle dysfunction is a major contributor to morbidity in chronic obstructive pulmonary disease (COPD), assessment of skeletal muscle, and diaphragm function is not routinely performed in COPD patients. OBJECTIVES: (1) The aim is to assess muscle dysfunction in COPD by measuring the zone of apposition of diaphragm, diaphragm excursion, thickness of diaphragm, and rectus femoris cross-sectional area (RFCSA) with ultrasonography. (2) To correlate the above assessments with spirometric parameters; notably forced expiratory volume in 1 s (FEV(1)). METHODS: Twenty-four consecutive stable COPD patients and 18 controls were included after obtaining written informed consent. Demographic and clinical data, spirometric values, 6-min walk distance, and sonographic parameters mentioned above were compiled for the analysis. RESULTS: All included participants were male with a mean age of 62.5 ± 8.4 years. The mean FEV(1) in cases was 1.12 ± 0.4 L versus 2.41 ± 0.5 L in controls. The diaphragm thickness (1.8 ± 0.5 mm vs. 2.2 ± 0.6 mm; P = 0.005) and RFCSA was significantly lower in COPD patients (4.8 ± 1.3 cm(2) vs. 6.12 ± 1.2 cm(2); P = 0.02). However, diaphragm excursion (5.35 ± 2.8 cm vs. 7 ± 2.6 cm) although lower in COPD patients, was not significantly different between the groups. Correlation between FEV(1) and ultrasound diaphragm measurements and RFCSA by Spearman's Rho correlation was poor (ρ = 0.2). CONCLUSION: Ultrasonographic assessment of the diaphragm and rectus femoris can be used as markers to assess skeletal muscle dysfunction in COPD as diaphragmatic function and RFCSA were lower in COPD patients.