Correlation of Diaphragm Ultrasound Parameters and Mechanical Ventilation Weaning

INTRODUCTION: Diaphragm thickness fraction (DTF) and diaphragmatic excursion (DE) have been shown to be associated with the outcome of weaning and extubation.(1,2) The aim of this study was to determine the correlation of these parameters and combining them with rapid shallow breathing index (RSBI) for predicting successful weaning. METHODS: Patients on pressure support ventilation as a part of weaning process after a minimum 48 hours of controlled ventilation were included. All demographic hemodynamic, ventilatory parameters along with RSBI were recorded. DE and DTF were recorded in a standardised manner during weaning trial.(3) At this stage patients were grouped into Successful weaning Versus Failed weaning groups. Patients in the Failed weaning group were switched back to controlled ventilation. Chi-square test, Fishers exact test and unpaired students T test were used for statistical analysis. RESULTS: 114 patients were included in this study. Mean age of patients was 59.04 ± 19.32 years. 78.1% cases had RSBI < 105 and 21.9% >105. DTF was >30% in 53.5% and <30% in 46.5% DE was ≥1.4cm in 52.3% and and <1.4 cm in 47.7%. RSBI, DTF and DE were studied independently and combined together to predict successful weaning. 30 patients had all 3 parameters predicted successful weaning i.e. RSBI<105, DTF>30% and DE> 1.4 cm whereas 18 patients had all 3 parameters predicted weaning failure i.e. RSBI > 105, DTF< 30% and DE< 1.4 cm. 66/114 patients either had only 1 or 2 variables predicting the success of weaning. Diagnostic efficacy measures of all 3 parameters combined together are as shown in Table 1. CONCLUSION: We conclude that combination of 3 indices viz DTF, DE and RSBI is associated with better prediction of weaning from mechanical ventilation.