Diaphragmatic Ultrasonography in Difficult Weaning

Weaning from mechanical ventilation (MV) is a gradual process that includes several stepsuntil the complete withdrawal of ventilatory support. Difficult weaning is defined asweaning completed only after the first attempt to withdraw the patient from ventilatorysupport, that is, a patient who failed the first spontaneous breathing trial (SBT). Theuse of ultrasound (US) to assess diaphragmatic and extradiaphragmatic muscles, such asthe parasternal muscles, has been employed to determine diaphragmatic dysfunction andventilatory effort, contributing to the decision‐making process regarding weaning. Amongthe tools used for bedside monitoring and evaluation of patients are ventilatoryvariables that indicate an adequate level of ventilatory assistance in spontaneous modesthrough ventilatory drive, such as P0.1 (occlusion pressure in the first 100 ms) andassessment of ventilatory effort‐inspiratory muscle pressure (Pmus)‐which have alsocontributed to the downscaling of ventilatory support. However, there is still noconsensus in the literature regarding predicted values or the effective role of thesetools as predictors of weaning during the spontaneous breathing trial (SBT). Theavailable studies investigating the relationship between diaphragmatic US, throughmeasurements of diaphragmatic excursion and thickening fraction, and weaning failure frommechanical ventilation are mostly observational, which limits the strength of the currentevidence. Therefore, it is essential to conduct randomized clinical trials, which arestill unprecedented on this topic, to more robustly assess the efficacy of this techniqueas a decision‐support tool during the weaning process, thereby contributing to moreprecise clinical practice. OBJECTIVES: The primary objective of this study is to evaluatethe effect of diaphragmatic US use on ventilator‐free days in patients with difficultweaning. The secondary objective is to analyze the relationship between the ventilatoryvariables P0.1 and Pmus, diaphragmatic US, and parasternal muscle recruitment during theSBT. METHODS: This is a randomized clinical trial, following CONSORT recommendations,which will be prospectively registered on the ClinicalTrials platform. Patients will beincluded after failing the first SBT. Subsequently, they will be randomized into twogroups: In the shared US group, the results of diaphragmatic assessment via US will beshared with the attending team for decision‐making regarding extubation. In the secondgroup, the non‐shared US group, the attending team will not have access to thediaphragmatic assessment for decision‐making. EXPECTED RESULTS: It is expected that theshared US group of patients will have a shorter duration of MV and a lower number ofextubation failures.