Role of diaphragm ultrasound in weaning mechanically ventilated patients: A prospective observational study

Background and Aims: Weaning from mechanical ventilation based on clinical parameters and rapid shallow breathing index (RSBI) is associated with a higher weaning failure. Bedside ultrasound of the diaphragm is gaining popularity to assess the diaphragm function. The aim of our study was to determine the use of diaphragm ultrasound in weaning ventilated patients. Methods: This prospective study was done on 200 adult patients on mechanical ventilation for more than 24 h. After meeting the clinical weaning criteria, a spontaneous breathing trial (SBT) was performed. RSBI was recorded and a bedside ultrasound of the diaphragm was performed to measure diaphragmatic excursion (DE) and diaphragm thickening fraction (DTF) before extubation. We assessed the predictability of weaning success of RSBI, DE and DTF by determining the area under the receiver operating characteristic (AUROC) curve and Youden's index. The requirement of non-invasive ventilation or re-intubation within 48 h was considered a weaning failure. Results: Out of the 200 patients studied, 171 were successfully weaned. The AUROC values for RSBI, DTF, DE, RSBI-DTF and RSBI-DE for successful weaning prediction were 0.422, 0.654, 0.809, 0.656 and 0.807, respectively. The predictability using cut-off values were DE >1.21 cm (sensitivity 94%, specificity 71%, Youden's index 0.65), DTF >37% (sensitivity 80%, specificity 52%, Youden's index 0.31) and RSBI <82 (sensitivity 94%, specificity 31%, Youden's index 0.25). Conclusion: Diaphragm ultrasound helps in predicting successful weaning in mechanically ventilated patients. Both DE and DTF showed a higher specificity than RSBI and a combination of RSBI-DE and RSBI-DTF was better than using RSBI alone.