[Value of the diaphragm movement index tested by ultrosonography for ventilation weaning]

To evaluate the diaphragm movement index of mechanical ventilation weaning patients by ultrosonography, and to explore its value for weaning.

Forty patients undergoing invasive mechanical ventilation for at least 48 hours admitted to emergency intensive care unit (EICU) of Hunan Provincial People's Hospital from September 2017 to February 2018 were enrolled. Low level pressure support ventilation (PSV) was used for spontaneous breathing test (SBT), and bedside M-mode ultrasonography was used to assess the diaphragm movement index of the patient within 1 hour of SBT, including the excursion of the diaphragm, diaphragmatic-rapid shallow breathing index (D-RSBI). The rapid shallow breathing index (RSBI) was measured by ventilator. The patients who met the clinical weaning criteria were weaned. According to the success or failure of the weaning, the patients were divided into the successful weaning group and the failure weaning group. The receiver operating characteristic (ROC) curve was used to evaluate the predictive value of each indicator to the failure of the weaning.

A total of 40 patients were enrolled in the final analysis, including 28 patients in the successful weaning group and 12 patients in the failure weaning group. The excursion of the diaphragm in the failure weaning group was significantly less than that in the successful weaning group (mm: 9.56±2.13 vs. 13.66±4.10, P < 0.01), and the D-RSBI and RSBI were significantly higher than those in the successful weaning group [D-RSBI (times×min^-1×mm^-1): 2.06±0.68 vs. 1.44±0.66, RSBI (times×min^-1×L^-1): 61.70±25.00 vs. 44.91±14.51, both P < 0.05]. The area under the ROC curve (AUC) of diaphragm displacement, D-RSBI, and RSBI was 0.830, 0.851 and 0.711, respectively, and the predicted value of diaphragm excursion and D-RSBI was higher. When the optimal critical value of diaphragmatic excursion was 11.15 mm, the sensitivity of predicting weaning failure was 83.3%, the specificity was 71.4%; when the optimal critical value of D-RSBI was 1.42 times×min^-1×mm^-1, the sensitivity of predicting the failure of weaning was 91.7%, and the specificity was 82.1%.

Diaphragm excursion and D-RSBI of the diaphragmatic ultrosonography index could accurately predict the failure of the weaning, which was superior to the traditional RSBI in guiding weaning.