Prediction of Loss of Muscle Mass in Sarcopenia Using Ultrasonic Diaphragm Excursion

The diagnosis of sarcopenia is based on the mass and function of appendicular skeletal muscle. It is not clear whether diaphragm excursion is related to muscle mass loss. We try to fill the gap by measuring ultrasonic diaphragm excursion during quiet breathing (Dq) and forced deep breathing (Df) and test whether they could predict the muscle mass loss in sarcopenia.

The subjects are recruited from the elderly patients diagnosed with pulmonary nodules in community physical examination. According to the definition, the subjects were divided into group A (who did not meet the diagnostic criteria for muscle mass loss in sarcopenia) and group B (who met the criteria). Participants were assessed for ultrasonic diaphragm excursion, pulmonary function, and cardiopulmonary exercise testing. Logistic regression was used to assess the correlation between right diaphragm excursion and skeletal muscle mass, and receiver-operating characteristic curve (ROC) was applied to determine the best threshold.

We recruited 64 elderly participants: 52 in group A (39 males) and 12 in group B (8 males). The Df in group A were higher than in group B (6.02 (5.44-6.60) vs. 4.31 (3.53-5.09) cm, P=0.008). The difference also exists in FVC, FEV1.0, PEF, Pimax, WRmax, and VO₂max, but neither in Dq. Logical regression showed that Df was negatively related to muscle mass (B = -0.525, OR = 0.591 (0.378-0.926), P=0.022), even after adjusted age. Based on ROC, a cutoff value of 5.27 cm (AUC = 0.7783, P=0.0028) was selected, and Df ≤ 5.27 cm indicates the increase in odds of existing muscle mass loss.

Ultrasonic diaphragm excursion in forced deep breath is helpful for predicting muscle mass loss in sarcopenia. The trial is registered with ChiCTR1800019742.