探讨急性呼吸窘迫综合征（ARDS）机械通气患者早期膈肌萎缩的发生情况及对撤机结局的影响。

选取2019年1月至2021年6月入住宁波市医疗中心李惠利医院东部院区重症医学科的53例ARDS并接受机械通气治疗患者，采用床旁超声连续监测机械通气后即刻、72 h的吸气末膈肌厚度（DTei）和呼气末膈肌厚度（DTee），定义机械通气后72 h的DTee ≤ 2 mm为早期膈肌萎缩，并将患者分为早期膈肌萎缩组（A组，27例）和非萎缩组（B组，26例）。比较两组患者的一般资料、急性病生理学和长期健康评价（APACHE）Ⅱ评分、机械通气后即刻及72 h的DTei和DTee、撤机结局、机械通气时长以及DTei、DTee与ARDS患者撤机结局的相关性，采用受试者工作特征（ROC）曲线确定预测拔管成功的最佳截断值。

A组患者机械通气72 h肺泡动脉氧分压差[P（A-a）O₂][（210 ± 118）mmHg vs.（155 ± 63）mmHg，t = 4.344，P = 0.042]和机械通气时间[188.0（112.0，281.0）h vs. 92.5（71.8，167.8）h，t = 2.642，P = 0.008]均大于B组，而撤机成功情况（8/27 vs. 24/26，χ² = 21.751，P < 0.001）、机械通气后72 h DTei[（0.224 ± 0.067）cm vs.（0.312 ± 0.094）cm，t = 3.933，P < 0.001]及72 h DTee[（0.159 ± 0.027）cm vs.（0.268 ± 0.082）cm，t = 6.570，P < 0.001]均明显低于B组。Spearman相关分析结果显示，机械通气后72 h DTei（r = 0.337，P = 0.014）及72 h DTee（r = 0.503，P < 0.001）均与机械通气撤机成功呈正相关。ROC曲线分析结果显示，ARDS患者机械通气后72 h DTei[曲线下面积（AUC）= 0.699，95%置信区间（CI）（0.557，0.817），P = 0.009]和72 h DTee[AUC = 0.797，95%CI（0.664，0.895），P < 0.001]均对机械通气撤机成功具有预测价值，二者最佳截断值分别为0.240 cm和0.200 cm，且后者预测撤机成功的特异度高于前者（90.5% vs. 71.4%）。

ARDS机械通气患者早期膈肌萎缩的出现与不良撤机结局密切相关，机械通气后72 h DTei和72 h DTee均可用来预测撤机结局，相较于72 h DTei，72 h DTee是指导预测撤机结局的较好指标。

To investigate the occurrence of early diaphragmatic atrophy in mechanically ventilated patients with acute respiratory distress syndrome (ARDS) and evaluate its influence on the outcome of weaning.

A total of 53 mechanically ventilated patients with ARDS admitted to the ICU of Ningbo Medical Center LiHuili Eastern Hospital from January 2019 to June 2021 were enrolled. Diaphragmatic thickness at the end of inspiration (DTei) and diaphragmatic thickness at the end of expiration (DTee) were measured by bedside ultrasound immediately and after 72 h of mechanical ventilation respectively. We defined DTee ≤ 2 mm after 72 h of mechanical ventilation as early diaphragmatic atrophy and patients were divided into the early diaphragmatic atrophy group (group A, n = 27) and the normal group (group B, n = 26) accordingly. The differences in general information, acute physiology and chronic health evaluation (APACHE) Ⅱ score, DTei and DTee immediately and after 72 h of mechanical ventilation, success rate of extubation, and duration of mechanical ventilation between the two groups of patients were compared. The relationships among DTei, DTee and the outcome of weaning were also analyzed. The receiver operating characteristic (ROC) curve was used to assess the optimal cut-off value of DTei, DTee in predicting extubation success.

The alveolar-arterial oxygen pressure difference [P(A-a)O₂] after 72 h of mechanical ventilation [(210 ± 118) mmHg vs. (155 ± 63) mmHg, t = 4.344, P = 0.042] and the duration of mechanical ventilation [188.0 (112.0, 281.0) h vs. 92.5 (71.8,167.8) h, t = 2.642, P = 0.008] in group A were both significantly higher than those in group B accompany with lower success rate of extubation (8/27 vs. 24/26, χ² = 21.751, P < 0.001), lower DTei [(0.224 ± 0.067) cm vs. (0.312 ± 0.094) cm, t = 3.933, P < 0.001] and lower DTee [(0.159 ± 0.027) cm vs. (0.268 ± 0.082) cm, t = 6.570, P < 0.001] after 72 h of mechanical ventilation. Spearman's correlation analysis revealed that the DTei (r = 0.337, P = 0.014) and DTee (r = 0.503, P < 0.001) after 72 h of mechanical ventilation were both positively correlated with extubation success. ROC curve analysis showed that the DTei [area under the curve (AUC) = 0.699, 95% confidence interval (CI) (0.557, 0.817), P = 0.009] and DTee [AUC = 0.797, 95%CI (0.664, 0.895), P < 0.001] after 72 h of mechanical ventilation in ARDS patients both had predictive value for successful mechanical ventilation. The optimal cut-off values are 0.240 cm and 0.200 cm, respectively, with the specificities of 71.4% and 90.5%, respectively.

The occurrence of early diaphragmatic atrophy in mechanically ventilated patients with ARDS is closely related to the adverse weaning outcome. The DTei and DTee after 72 h of mechanical ventilation are both valuable in predicting extubation success of ARDS patients, in which the DTee is more accurate and may be a better indicator compared with the DTei.