Pulmonary Physicians of Norwich, Norwich, CT.
Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, Hofstra-Northwell School of Medicine, New Hyde Park, NY.
Chest. 2018 May;153(5):1213-1220. doi: 10.1016/j.chest.2018.01.007. Epub 2018 Jan 17.
The diaphragmatic response to increased mechanical load following withdrawal of mechanical ventilation is critical in determining the outcome of extubation. Using ultrasonography, we aimed to evaluate the performance of the excursion-time (E-T) index-a product of diaphragm excursion and inspiratory time, to predict the outcome of extubation.
Right hemidiaphragm excursion, inspiratory time, and E-T index were measured by ultrasonography during mechanical ventilation: (1) on assist-control (A/C) mode during consistent patient-triggered ventilation, (2) following 30 min during a spontaneous breathing trial (SBT), and (3) between 4 and 24 h following extubation. These measurements were correlated with the outcome of extubation. Patients in the "failure" group required reintubation or noninvasive ventilation within 48 h of extubation.
Of the 73 patients studied, 20 patients failed extubation. During SBT, diaphragm excursion was 1.65 ± 0.82 and 2.1 ± 0.9 cm (P = .06), inspiratory time was 0.89 ± 0.30 and 1.11 ± 0.39 s (P = .03), and the E-T index was 1.64 ± 1.19 and 2.42 ± 1.55 cm-s (P < .03) in the "failure" and "success" groups, respectively. The mean change in E-T index between A/C and SBT was -3.9 ± 57.8% in the failure group and 59.4 ± 74.6% in the success group (P < .01). A decrease in diaphragmatic E-T index less than 3.8% between A/C and SBT had a sensitivity of 79.2% and a specificity of 75%, to predict successful extubation.
Diaphragm E-T index measured during SBT may help predict the outcome of extubation. Maintenance or increase in diaphragm E-T index between A/C and SBT increases the likelihood of successful extubation.
在机械通气撤机后，膈肌对机械负荷增加的反应对于预测拔管结果至关重要。本研究使用超声评估了呼气时间（E-T）指数——膈肌位移与吸气时间的乘积，以预测拔管结果。
在机械通气时通过超声测量右膈肌位移、吸气时间和 E-T 指数：（1）在辅助控制（A/C）模式下，在持续的患者触发通气时；（2）在自主呼吸试验（SBT）进行 30min 后；（3）在拔管后 4-24h。这些测量结果与拔管结果相关。在拔管后 48h 内需要重新插管或无创通气的患者被归入“失败”组。
在 73 名研究患者中，有 20 名患者拔管失败。在 SBT 期间，“失败”组和“成功”组的膈肌位移分别为 1.65±0.82cm 和 2.1±0.9cm（P=0.06），吸气时间分别为 0.89±0.30s 和 1.11±0.39s（P=0.03），E-T 指数分别为 1.64±1.19cm·s 和 2.42±1.55cm·s（P<0.03）。在“失败”组，A/C 和 SBT 之间 E-T 指数的平均变化为-3.9±57.8%，而在“成功”组为 59.4±74.6%（P<0.01）。A/C 和 SBT 之间 E-T 指数减少小于 3.8%对预测拔管成功的敏感性为 79.2%，特异性为 75%。
SBT 期间测量的膈肌 E-T 指数可能有助于预测拔管结果。A/C 和 SBT 之间膈肌 E-T 指数的维持或增加增加了拔管成功的可能性。
