[Comparison of ultrasound-based area measurement with diaphragmatic excursion measurement for assessing...

Objective: To compare the diagnostic performance of ultrasound-based area measurement with that of diaphragmatic excursion measurement for assessing sepsis-induced diaphragmatic dysfunction (SIDD). Methods: We prospectively enrolled 39 hospitalized patients with sepsis from the Department of Respiratory and Critical Care Medicine, Shengjing Hospital of China Medical University (February 2024-February 2025), and 47 healthy volunteers as controls. Bedside ultrasound was used to measure lateral thoracic area change and diaphragmatic excursion during quiet and deep breathing. Between-group differences were assessed with the Mann-Whitney U test. Receiver operating characteristic (ROC) curves were constructed and the areas under the curve (AUCs) calculated to evaluate the early predictive value of each measurement for SIDD under different respiratory states. Results: (1) During quiet breathing, lateral thoracic area change was significantly lower in the sepsis group [13.42 (8.35, 19.60) cm²] than in controls [22.02 (16.70, 31.62) cm²] (Z=-3.214, P=0.001), whereas diaphragmatic excursion did not differ significantly between groups [13.04 (10.04, 15.80) mm vs. 14.40 (10.84, 18.80) mm; Z=-1.258, P=0.208]. During deep breathing, both lateral thoracic area change [29.26 (19.08, 38.27) cm² vs. 78.96 (59.18, 106.14) cm²] and diaphragmatic excursion [23.21 (17.79, 27.03) mm vs. 40.83 (31.20, 45.82) mm] were significantly lower in the sepsis group than in controls (both P<0.05). (2) ROC analysis yielded AUCs for lateral thoracic area change of 0.702 (quiet breathing) and 0.964 (deep breathing), and for diaphragmatic excursion of 0.579 (quiet breathing) and 0.856 (deep breathing). Conclusions: Ultrasound-based area measurement can detect early sepsis-induced diaphragmatic dysfunction during quiet breathing and does not require active breathing cooperation from the patient. It therefore has broader clinical applicability than diaphragmatic excursion measurement. Across different respiratory states, its diagnostic performance is significantly superior to that of excursion measurement, demonstrating greater diagnostic value.