_{【】ObjectiveTo establish the phrenic ultrasonic rating scale and explore the predictive value of the phrenic ultrasonic rating scale for the success of mechanical ventilation patients. MethodsThe 64 cases of mechanical ventilation patients admitted to EICU in sanmenxia hospital of the Yellow River from October 2016 to October 2018 were observed. The duration of ventilation was longer than 48h, and the patients reached the standard of spontaneous breathing test (SBT) [1]. Bedside ultrasound was performed by the clinician to record the changes in the thickness of the diaphragm during SBT, the range of motion of bilateral diaphragms, and tidal volume and respiratory frequency. Patients were divided into success group and failure group according to their offline success or failure. By ROC subjects working curve drawing, analysis the SBT diaphragm thickness change, diaphragm motion amplitude, diaphragm shallow breathing fast index (D - RSBI) optimal estimation of weaning failure happened and the critical value, and according to the optimal threshold to the continuity of related variables into two categories, the multi-factor Logistic regression analysis, according to the size of the OR value, to value assignment of independent risk factors, assessment is established. The probability of offline success was predicted by the score table. ResultsThe risk of patients with failed withdrawal was divided into three levels according to the phrenic ultrasound rating scale: the low-risk group (0-2 points), the medium-risk group (3-6 points) and the high-risk group (7-8 points). The failure rate of withdrawal in the low-risk group was about 12.5%, the failure rate of withdrawal in the medium-risk group was about 53.7%, and the failure rate of withdrawal in the high-risk group was about 84.8%. ConclusionThe phrenic ultrasound scale was predictive in assessing the risk of weaning patients with mechanical ventilation.}