Abstract: Objective: To investigate the relationship between bioelectrical impedance phase angle (PA) and nutritional status of ICU patients with sepsis, and to determine the critical value of PA. Methods: A total of 98 sepsis patients admitted to ICU were selected by convenience sampling method. General information of patients was collected, and laboratory test results were recorded. Body composition analysis was performed using bioelectrical impedance technology and PA values were recorded. Malnutrition was diagnosed by Global Leadership Initiative on Malnutrition (GLIM) criteria. The receiver operating characteristic (ROC) curve of PA was drawn to find the best cut-off value, and the correlation between PA and nutrition-related indicators was analyzed. Results: Compared with the normal PA group, patients in the low PA group had a higher frequency of mechanical ventilation use and longer hospital stays, with statistically significant differences (P<0.05). PA was positively correlated with bone mineral content, skeletal muscle mass, and negatively correlated with ECW/TBW, acute physiology and chronic health evaluation II and the difference was statistically significant (P<0.05). The critical value of PA in ICU patients with sepsis was 3.25°, the area under the ROC curve was 0.631, the sensitivity was 0.632, the specificity was 0.633 and the Youden index was 0.265. Conclusion: PA is closely related to the nutritional status of ICU patients with sepsis, and the critical value of PA for predicting malnutrition is 3.25°, indicating that PA can serve as an objective screening tool for malnutrition in these patients. This provides a basis for clinical nurses to identify high-risk patients early and develops personalized nutritional support strategies.

Key words: Sepsis, Nutritional assessment, Phase angle, Bioelectrical impedance technique

摘要： 目的：探讨生物电阻抗相位角（Phase Angle，PA）与ICU脓毒症患者营养状况的关系，确定相位角临界值。方法：采取便利抽样法，选取98例入住ICU的脓毒症患者，收集患者基本资料及实验室检查结果。使用生物电阻抗技术进行人体成分分析，记录相位角值。分析相位角与营养相关指标的相关性，以全球营养领导层倡议的营养不良标准诊断营养不良，绘制相位角的受试者工作特征（ROC）曲线，寻找最佳截断值。结果：与正常相位角组相比，低相位角组患者的机械通气使用频率更高，住院时间更长，差异具有统计学意义（P＜0.05）；在相关性分析中，相位角与骨矿物质含量、骨骼肌质量呈正相关，与细胞外液/总水分、急性生理与慢性健康域评分呈负相关，差异有统计学意义（P＜0.05）。ICU 脓毒症患者相位角临界值为 3.25°，ROC 曲线下面积为 0.631，敏感性为0.632，特异性为 0.633，约登指数为 0.265。结论：相位角与 ICU 脓毒症患者营养状况密切相关，其预测营养不良临界值为 3.25°，提示相位角可作为ICU脓毒症患者营养不良的客观筛查工具，为临床护士早期识别高风险患者、制定个性化营养支持策略提供参考依据。

关键词: 脓毒症, 营养状况, 相位角, 生物电阻抗技术