目的 探讨床旁超声评估四肢骨骼肌和膈肌对老年ICU获得性衰弱（ICU-AW）的诊断价值。 方法 纳入2023年3月至2024年4月杭州市余杭区第二人民医院重症监护病房收治的47例老年重症患者，平均年龄74.51岁，采用医学研究委员会（MRC）评分进行肌力评估，期间连续2次且间隔24 h，当MRC评分< 48分纳入ICU-AW组（20例），≥ 48分纳入非ICU-AW组（27例）。使用超声测量患者入住ICU首日、第3天（D3）及第7天（D7）上下肢骨骼肌厚度及膈肌参数，并且计算不同时间节点的上下肢骨骼肌厚度缩率，比较两组肌肉超声指标的差异，通过ROC曲线分析上下肢骨骼肌和膈肌相关参数对ICU-AW的诊断价值。 结果 两组在性别、年龄、BMI、APACHEⅡ评分、SOFA评分、机械通气例数及脓毒症例数比较差异有统计学意义（均P < 0.05）。与非ICU-AW组相比，D3 ICU-AW组股四头肌［股中间肌（VI）、总股四头肌（QF）］的萎缩率较高，膈肌移位度（DE）较低（P < 0.05）；D7 ICU-AW组股四头肌［股直肌（RF）、股中间肌（VI）及总股四头肌（QF）］的萎缩率较高，膈肌参数［膈肌位移度（DE）及膈肌厚度分数（DTF）］较低（均P < 0.05）。通过ROC曲线分析：D7 ΔRF-MLT萎缩率预测ICU-AW的临界值为9.9%，AUC为0.743，敏感度为75.0%，特异度为77.8%；D7 ΔVI-MLT萎缩率预测ICU-AW的临界值为5.69%，AUC为0.828，敏感度为80.0%，特异度为77.8%；D7 ΔQF-MLT萎缩率预测ICU-AW的临界值为16.96%，AUC为0.835，敏感度为60.0%，特异度为88.9%；D7 DE预测ICU-AW的临界值为1.67 cm，AUC为0.818，敏感度为75.0%，特异度为85.2%；D7 DTF预测ICU-AW的临界值为33.96%，AUC为0.889，敏感度为80.0%，特异度为85.2%；D7膈肌参数联合股四头肌参数预测ICU-AW的AUC为0.976，敏感度为80.0%，特异度为100%。 结论 床旁超声测量股四头肌萎缩率联合膈肌参数可尽早识别和诊断ICU-AW。

Objective To investigate the diagnostic value of skeletal muscle and diaphragm muscle in the extremities， as assessed by bedside ultrasound， for ICU?acquired weakness in elderly patients. Methods A total of 47 elderly patients with severe illness， admitted to the intensive care unit （ICU） of the Second People's Hospital of Yuhang District from March 2023 to April 2024， were included in this study. The average age of the patients was 74.51 years. Medical Research Council （MRC） scores were assessed twice within a 24?hour interval. Among them， when MRC score < 48， 20 cases were classified into the ICU?AW group， while the remaining 27 cases formed the non?ICU?AW group with MRC score ≥ 48. Ultrasound measurements for lower extremity skeletal muscle thickness and diaphragm parameters were conducted on the first day， third day， and seventh day after ICU admission. The rate of shrinkage in upper and lower extremity skeletal muscle thickness at different time points was calculated. Differences in ultrasound parameters between the two groups were compared， and ROC curve analysis was performed to evaluate the diagnostic value of upper and lower extremity skeletal muscle as well as diaphragm parameters for ICU?AW. Results Significant differences were observed in gender， age， BMI， APACHEⅡ score， SOFA score， number of mechanical ventilation cases， and number of sepsis cases between the two groups （P < 0.05）. Compared to the non?ICU?AW group， the ICU?AW group exhibited higher rates of atrophy in quadriceps femoris （RF） and total quadriceps femoris （QF） on day 3 and a lower degree of diaphragm displacement （DE） （P < 0.05）. On day 7， the ICU?AW group showed higher rates of atrophy in quadriceps femoris ［rectus femoris （RF）， intermedius femoris （VI）， and total quadriceps femoris （QF）］ along with lower diaphragm parameters ［diaphragm displacement degree （DE） and diaphragm thickness fraction（DTF）］ （P < 0.05）. According to ROC curve analysis， the critical value of ICU?AW predicted by ΔRF?MLT atrophy rate on day 7 was 9.9%， AUC was 0.743， sensitivity was 75.0% and specificity was 77.8%. On day 7， the critical value of ICU?AW was 5.69%， AUC was 0.828， sensitivity was 80.0%， and specificity was 77.8%. On day 7， the critical value of ICU?AW was 16.96%， AUC was 0.835， sensitivity was 60.0%， and specificity was 88.9%. On day 7， DE predicted that the critical value of ICU?AW was 1.67 cm， AUC was 0.818， sensitivity was 75.0%， and specificity was 85.2%. On day 7， DTF predicted that the critical value of ICU?AW was 33.96%， AUC was 0.889， sensitivity was 80.0%， and specificity was 85.2%. On day 7， the AUC of ICU?AW was 0.976， the sensitivity was 80.0%， and the specificity was 100%. Conclusion The quadriceps atrophy rate and diaphragm parameters measured by bedside ultrasound can identify and diagnose ICU?AW as early as possible.