8: Ultrasonographic assessment of diaphragmatic parameters for predicting weaning outcome in patients on mechanical ventilation in the intensive care unit setting.

Abstract

Background and Aims:The aim of this study was to ultrasonographically assess diaphragmatic parameters for predicting weaning outcome in patients on mechanical ventilation in the intensive care unit ( ICU ) setting. The primary objective was to assess the diagnostic accuracy of diaphragmatic excursion(DE) and diaphragmatic thickness fraction(DTF) by ultrasonography to predict weaning outcome in patients on mechanical ventilation. The secondary objectives were: To correlate diaphragmatic dysfunction with re-intubation within 48 hours of extubationTo assess which of the two - DE) or DTF is a better predictor of weaning.To compare diaphragmatic rapid shallow breathing index (RSBI) with clinical RSBI. Methods:This cohort study was conducted on 50 adult patients of either sex, admitted in the ICU and scheduled to undergo extubation. The patient’s readiness to wean was assessed by clinical judgment. When the patient was ready to be weaned, he/she was put on pressure support ventilation (PSV). The pressure support was gradually reduced to 6cm H2O. If the patient remained stable and extubation was planned, T-piece trial was given. Baseline parameters (Heart rate, non invasive blood pressure, respiratory rate, tidal volume, RSBI, SpO2, signs of respiratory distress- nasal flaring, sweating, agitation, use of accessory muscles,arterial blood gas analysis, Maximum Inspiratory Pressure (MIP), Maximum Expiratory Pressure(MEP) were recorded.Results:DE and DTF were assessed ultrasonographically and diaphragmatic RSBI was later calculated. DE andDTF were found to have similar sensitivity (94.12% and 97.06%), specificity (75%), positive predictive values(88.89 and 88.19% respectively) and negative predictive values (85.71% and 92.31% respectively). Overall DTF was comparable to DE in terms of diagnostic accuracy (88% and 90% respectively). (p value=1)Conclusion:DE and DTF are rapid and non invasive ultrasonographic indices with a high diagnostic accuracy for predicting weaning outcome. They provide objective and accurate results and are comparable to each other for predicting weaning outcome. Diaphragmatic RSBI is a good predictor of weaning outcome and is comparable to clinical RSBI.Weaning outcomeDiaphragmatic excursion (mm)Diaphragmatic thickness fraction (%)Sensitivity (95% CI)94.12% (80.32%-99.28%)97.06% (84.67%-99.93%)Specificity (95% CI)75% (47.62%-92.73%)75% (47.62%-92.73%)AUC (95% CI)0.85 (0.72-0.93)0.86 (0.73-0.94)Positive Predictive Value (95% CI)88.89% (73.94%-96.89%)89.19% (74.58%-96.97%)Negative Predictive Value (95% CI)85.71% (57.19%-98.22%)92.31% (63.97%-99.81%)Diagnostic accuracy88.00%90.00%P after Comparison of sensitivity1P after Comparison of specificity1