Role of Ultrasound in Assessment of Diaphragmatic Function in COPD Patients during Weaning from Mechanical Ventilation

Abstract

COPD is a major cause of chronic morbidity and mortality throughout the world; many people suffer from this disease for years, and die prematurely from it or its complications. Predicting extubation outcome and preventing extubation failure is therefore an important task. Various weaning parameters have been suggested to be useful eg: rapid shallow breathing index (RSBI), maximum inspiratory pressure (Pimax), spontaneous tidal volume (VT), and trans-diaphragmatic pressure (Pdi), however the prediction rate of these parameters may not be satisfactory. Evaluating the strength of the respiratory muscles becomes important since the imbalance between respiratory demand and supply will lead to weaning failure through the development of respiratory muscle fatigue. Ultrasonography has been shown to be a promising tool in evaluating the diaphragmatic function. The aim of this work was to study the role of ultrasound in evaluating the movement of the diaphragm and its value in predicting the successful extubation in mechanically ventilated COPD patients in relation to other weaning parameters. The present study was conducted upon fifty patients (thirty mechanically ventilated COPD patients 73.3% had successful weaning and 26.7% had failed weaning) and twenty COPD patients not mechanically ventilated). As regard weaning from mechanical ventilation, many parameters were used to assess the patients as: tidal volume (VT) with sensitivity of 85.6%, specificity of 75% and accuracy of 84.6%, rapid shallow breathing index (respiratory rate divided by tidal volume, f/VT) with sensitivity of 88.7 %, specificity of 73.2 % and accuracy of 85%, maximum inspiratory pressure (PI max) with sensitivity of 82.5%, specificity of 62.6% and accuracy of 72.4%. However, these methods were limited by their invasive nature and dependency on maximal voluntary efforts of the patients. Also the prediction rate of these parameters may not be satisfactory so evaluating the diaphragmatic excursion became important. In this study the mean displacement of the diaphragm (DD) measured by the ultrasound during weaning from