Objective method in evaluating the evacuation timing of mechanical ventilation for neonatal respiratory distress syndrome（NRDS）.Methods selected. Bedside lung ultrasound score（LUS）was performed before the children extubation when they reached the clinical evacuation standard

LUS was measured by six-zone method

ten-zone method

twelve-zone method and fourteen-zone method in two groups.According to the results of evacuation

the children were divided into the success group（n=49）and the failure group（n=13）

the LUS of the two groups were compared. LUS was administered to the evacuation failure group before reintubation and before re-extubation.The ROC curve was used to analyze the diagnostic efficacy of LUS for the evacuation timing.ResultsThere were significantly difference in LUS between the two groups for different four method（all P<0.05）.In the failure group

the following pathology changers were found by lung ultrasonography:4 cases of obvious lung edema

5 cases of extensive lung consolidation

2 cases of extensive lung consolidation at the bottom of the lung

1 case of large atelectasis of the upper right lung

and 1 case of no abnormality in lung ultrasonography but cardiac dysfunction was found.Compared with the other three methods

the fourteen-zone lung ultrasound scoring method had a better diagnostic performance for the evacuation timing

taking40.5 point as the cutoff value to predict the risk of evacuation failure

the area under the curve was 0.965

the sensitivity was92.31%

and the specificity was 93.88%.Conclusion value in evaluating the evacuation timing of mechanical ventilation in NRDS

which can identify high-risk children with early failure of evacuation

guide further clinical diagnosis and treatment

and improve the success rate of evacuation.