The Predict Value Of Diaphragmatic Ultrasound During Spontaneous Breathing Trial Of Weaning Outcome In Critically Ill Patients

Objective: The aim of this study is to assess the value of diaphragmatic ultrasound at different time point during spontaneous breathing trial to predict the weaning outcome in critically ill patients.Methods: This was a prospective observation study conducted on the patients admitted to the emergency intensive care unit(EICU)of the second hospital of Hebei Medical University from August 2019 to January 2020.These patients had mechanical ventilated for more than 48 hours and were ready to wean.If the patients passed the screening test before weaning,they were put to spontaneous breathing test(SBT).If the patient cannot tolerate SBT,the trial will be discontinued immediately and the ventilation mode will switch to the mode used before the trial.Patients who pass 1-hour SBT will be extubated.3,30 and 60 minutes after the start of SBT,the right diaphragm excursion(DE),the right diaphragm thickening fraction(DTF)and the diaphragm contraction velocity(DCV)were measured by ultrasound,and the rapid shallow breathing index(RSBI)was calculated.According to weaning outcome,the patients were divided into two groups: success group and failure group.The relationship between DE,DTF and DCV measured at different time points and the weaning outcome were statistically analyzed.The predict value of these parameters in weaning were analyzed and evaluated with ROC curve.Results: 39 patients were included in this study,31 patients were successfully weaned and 8 patients failed.The failure rate of weaning was 20.5%.The clinical characteristics between the two groups had no significant difference(P > 0.05).And there was no significant difference in vital signs,PO2,PCO2 and oxygenation index between the two groups during SBT(P > 0.05).The RSBI of failure group was significantly higher than that of success group(P < 0.01).The difference of DE between the two groups during SBT was statistically significant(P = 0.024,0.006,0.005).30 minutes and 60 minutes after the initiation of SBT,the DTF in the failure group was significantly lower than that in the success group(P = 0.007,0.008).The cutoff value of diaphragm mobility was 12.1mm 60 minutes after the start of SBT.The sensitivity and specificity were 90.3% and 75% respectively.The area under ROC curve was 0.815(95% CI: 0.591-1.000).30 minutes after the start of SBT,the cut-off value of diaphragmatic thickening rate was 26% with a sensitivity of 90.3% and a specificity of 62.5%,and the area under ROC curve was 0.806(95% CI: 0.617-0.995).DCV is of little value in predicting the outcome of weaning.Conclusions: Diaphragmatic ultrasound can be used to evaluate the function of diaphragm during SBT to predict the outcome of weaning.