Diaphragm Ultrasound as a Novel Guide of Weaning From Invasive Ventilation

Abstract

Background: Predictive guides of weaning from invasive ventilation are often erroneous. Among the numerous parameters used in practice, the rapid shallow breathing index is one of the most accurate. Aim: The diaphragm thickening (DT) measured by ultrasound was evaluated as a weaning predictor compared with the rapid shallow breathing index(RSBI). Patient and Methods: A prospective study included 78 patients with COPD exacerbations. All patients were ventilated in pressure support through endotracheal tube. During spontaneous breathing trial (SBT), the right diaphragm was visualized in the zone of apposition using a 7.5 MHz linear ultrasound probe. DT was calculated as percentage from the following formula: Thickness at end inspiration − Thickness at end expiration / Thickness at end expiration. It was recorded at total lung capacity (TLC) and residual volume (RV). The RSBI was calculated. Weaning failure was defined as the inability to maintain spontaneous breathing for at least 48 hours, without any form of ventilatory support. Results: A significant difference between DT at TLC and RV was observed both in patients who succeeded SBT and patients who failed. DT was significantly different between patients who failed and patients who succeeded SBT. A cutoff value of a DT >40% was associated with a successful SBT with a sensitivity of 88%, a specificity of 92%, a positive predictive value (PPV) of 95%, and a negative predictive value (NPV) of 82%. On the other hand , RSBI Conclusions: DT assessed by ultrasound is an excellent predictor of weaning outcome in mechanically ventilated COPD patients.