Abstract No.: ABS1330: A prospective observational study on ultra-sound of the diaphragm in weaning mechanically ventilated patients

Abstract

Background and Aims:Weaning mechanically ventilated patients is a challenging task in the intensive care unit. Rapid shallow breathing index (RSBI) is a known weaning index to guide extubation. The aim of our study was to determine the use of diaphragm ultra-sound in weaning these patients.Methods:After obtaining ethics committee approval and Clinical Trials Registry India registration, this prospective study was performed on 200 patients on mechanical ventilation for more than 24 hours. After meeting clinical weaning criteria, spontaneous breathing trial (SBT) was performed for 1 hour to assess weaning and then trachea was extubated. Independent observers recorded RSBI and performed bedside ultra-sound of the diaphragm before extubation to measure diaphragm thickening fraction (DTF) and diaphragmatic excursion (DE). We assessed the predictability of weaning success with DTF and DE. Weaning failure was defined as the requirement of non-invasive ventilation or re-intubation within 48 h.Results:One hundred and seventy one patients out of 200 were successfully weaned. The area under the receiver operating characteristic curve (AUROC) values for RSBI, DTF, and DE for successful weaning prediction were 0.422, 0.654, and 0.809, respectively. The predictability using cut-off values were RSBI <82 (sensitivity 94%, specificity 31%, Youden’s index 0.25), DTF >37% (sensitivity 80%, specificity 52%, Youden’s index 0.31), and DE >1.21 cm (sensitivity 94%, specificity 71%, Youden’s index 0.65). The AUROC values for the combination of RSBI–DTF and RSBI–DE were 0.656 and 0.807, respectively.Conclusion:Diaphragm ultra-sound helps in determining weaning readiness in mechanically ventilated patients. Both DTF and DE showed a higher specificity than RSBI, and the combination of RSBI–DE and RSBI–DTF further increased the specificity in successful weaning.ParameterCut off rangeSensitivity %Specificity %PPV %NPV %Youden’s IndexAUROCRSBI<8294.031.089.045.00.250.422DTF (%)>37%79.551.790.730.00.310.654DE (cm)>1.2193.671.495.264.50.650.809RSBI-DTF> 0.85466.769.092.726.00.360.656RSBI-DE>0.73893.071.495.262.50.640.807