Introduction
Invasive mechanical ventilation (IMV) with positive pressure is widespread in pediatric intensive care units (PICUs), with at least one-third of children being mechanically ventilated.1,2. Prolonged IMV is associated with ventilator-related injury, increased nosocomial infection risk, longer sedation requirement3 and diaphragmatic atrophy4. Ultimately, children should be weaned from the ventilator once the clinical condition improves. However, the optimal timing of extubation is not easy to determine, considering both early and late extubation may affect clinical outcomes. Extubation failure is associated with poorer clinical outcomes in children, with a reported rate of 2.7 percent to 22%.3,5,6. Children’s weaning practices vary depending on hospitals, staff, and resources. Therefore, predictive indicators of successful extubation are needed. Several indices have been developed to predict weaning success and extubation failure, including the Rapid Shallow Breathing Index (RSBI = f/Vt); Maximal Inspiratory Pressure (MIP), Compliance Resistance Oxygenation Pressure Index (CROP); Volumetric Capnography; and Extubation Readiness Test7 (ERT). However, none of the above indices have been widely used in PICU practice except ERT8–10.
Due to the suppression of inspiratory effort, diaphragmatic atrophy occurs quickly in mechanically ventilated children, resulting in ventilator induced diaphragmatic dysfunction (VIDD), which is related to difficulties weaning from IMV, prolonged duration of stay, and other complications4,11,12. Additionally, high ventilator mandatory breathing rates, corticosteroids, and neuromuscular blockers aggravate VIDD13.
With the extensive use of ultrasound in critical care settings, detecting VIDD and predicting weaning outcomes using ultrasonographic diaphragm imaging have been clinical research hotspots in recent years. Several adult studies demonstrated that some structural indexes such as excursion, thickness and thickening fraction of diaphragm obtained with the point of care diaphragm ultrasound (DUS) have good predictive values on successful extubation14,15. Although various research has demonstrated that DUS may be used to examine children’s diaphragm functions16 and predict extubation failure17,18, there is a dearth of evidence regarding its use in weaning procedures.
This study aims to evaluate the predictive value of DUS in weaning outcomes in mechanically ventilated children and develop a more reliable tool for its use in pediatric intensive care units.