Objective  To compare the predictive value of rapid shallow breathing index (RSBI), diaphragm rapid shallow breathing index (D-RSBI) and diaphragm thickening rapid shallow breathing index(DT-RSBI) for weaning outcomes.

  Methods  Patients with mechanical ventilation duration of 48 hours and above who were ready to be weaned were selected. At the end or failure of spontaneous breathing test (SBT), diaphragmatic thickening rate (DTF) and diaphragmatic excursion(DE) were measured, respiratory rate and tidal volume were recorded simultaneously, D-RSBI and DT-RSBI were obtained by replacing the tidal volume of RSBI with DE and DTF in the computational formula, respectively. The patients who reached the weaning standard were weaned and were divided into successful group (n=19) and failed group (n=13) according to weaning results. The difference of each index between the two groups was compared. The Receiver Operator Characteristic (ROC) curve was used to evaluate the value of each index in predicting weaning outcomes.

  Results  DE, DTF, RSBI, D-RSBI and DT-RSBI showed significant differences between two groups (P < 0.05). DE and DTF could predict success of weaning(P < 0.05). The threshold values of DTF and DE in predicting weaning success were 20.50%and 0.91 cm, respectively. DT-RSBI, D-RSBI and RSBI could predict weaning failure (P < 0.05). Taking 14.44 breaths/(min·cm), 119.46 breaths/min and 66.83 breaths(min·L) as the threshold values, the areas under the curve (AUC) were 0.830, 0.810 and 0.773, respectively.

  Conclusion  D-RSBI and DT-RSBI are more accurate in predicting weaning outcomes than RSBI, and D-RSBI has the highest accuracy, which could guide weaning in stead of RSBI.