Objective To investigate the value of ultrasound detection of diaphragm contraction velocity in predicting mechanical ventilation withdrawal.

Methods From July 2016 to February 2019, 94 patients requiring mechanical ventilation in the Emergency Department of Zhongshan Hospital in Shanghai were studied, including 61 patients with acute respiratory distress syndrome and 33 patients after cardiopulmonary resuscitation. The 94 patients were divided into successful weaning group (n=73) and failure weaning group (n=21). The diaphragm was examined by ultrasound at 0 min, 5 min, and 30 min of spontaneous breathing test. The diaphragm contraction velocity was calculated according to the diaphragm displacement and inspiration time. The receiver operating characteristic (ROC) curve was plotted to predict the diaphragm contraction velocity and predict the value of successful weaning.

Results Diaphragmatic dysfunction was found in 19 patients (90.48%) in the failure group and 41 patients (56.16%) in the successful weaning group. There was a significant difference between the two groups (P < 0.05). With the prolongation of spontaneous breathing test time, the diaphragm contraction speed of successful weaning group and failure weaning group increased (P < 0.05). The diaphragm contraction speed of successful weaning group was lower than that of failure weaning group at 5 and 30 minutes of spontaneous breathing (P < 0.05). At 0 min and 5 min of spontaneous breathing, the area under the curve (AUC) predicting successful weaning was 0.469 and 0.501, respectively. The predictive value was the highest at 30 min, and the AUC was 0.791, sensitivity and specificity were 75.32% and 69.37%, respectively (P < 0.05).

Conclusions Ultrasound is a simple method to detect diaphragm function. When the diaphragm contraction velocity is less than 1.57 cm/s at 30 minutes of spontaneous breathing test, it is of high value to predict successful weaning.