Prediction of weaning outcomes from mechanical ventilation in critically ill patients based on the combination of ultrasound parameters of the heart, lung, and diaphragm: a prospective observational cohort study.

Background: Postextubation distress in critically ill patients with successful spontaneous breathing trials (SBTs) is unfavorable for prognosis. This study aimed to determine whether the combined application of multimodal ultrasound parameters of the heart, lung, and diaphragm can predict the mechanical ventilation weaning outcome among critically ill patients.

Methods: From December 2022 to December 2023, a total of 74 patients (aged over 18 years old) mechanically ventilated for more than 48 hours and prepared for an SBT were selected from the Department of Critical Care Unit, Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School. Patients who met the criteria for weaning were prepared to undergo a 30-minute SBT, during which the heart, lungs, and diaphragm of the patients were examined via ultrasound. According to the weaning outcomes, patients were divided into a success group and a failure group. Ultrasound parameters with statistical significance in univariate analysis were incorporated into a binary logistic regression model to identify the independent influencing factors of weaning outcomes. The receiver operating characteristic (ROC) curve was plotted, and the area under the curve (AUC) was calculated for statistical analysis.

Results: Out of the 74 included patients, 23 failed weaning. There were significant differences in diaphragm excursion (DE), diaphragm thickening fraction (DTF), bilateral lung ultrasound score (LUS), total LUS, and left ventricular ejection fraction (LVEF) between the success and failure groups (P<0.05). The predictive performance of individual ultrasound parameters was as follows: LVEF achieved an AUC of 0.742 [95% confidence interval (CI): 0.642-0.842; P<0.001], with optimal thresholds of 58.05% (sensitivity: 76.5%; specificity: 69.6%); LUS achieved an AUC of 0.837 (95% CI: 0.738-0.936; P<0.001), with an 80.4% sensitivity and 82.6% specificity at a cutoff value of 17.50. DE yielded an AUC of 0.895 (95% CI: 0.821-0.969; P<0.001), with an 82.4% sensitivity and a 95.7% specificity at a cutoff value of 1.205 cm; DTF reached an AUC of 0.896 (95% CI: 0.827-0.965; P<0.001), with a 68.6% sensitivity and a 100% specificity at a cutoff value of 22.75%. A composite model integrating LVEF, LUS, DE, and DTF achieved an AUC of 0.951 (95% CI: 0.907-0.996; P<0.001), with an 88.2% sensitivity and a 95.7% specificity.

Conclusions: Ultrasound parameters of the heart, lungs, and diaphragm provide critical information on cardiopulmonary and diaphragmatic function during SBT. Weaning failure is more common when LUS is increased and LVEF, DE, and DTF are decreased. The combination of these three aspects can improve the accuracy of predicting weaning outcomes.