Performance of objective cough measurement, diaphragmatic contraction velocity, and spontaneous breathing trial for predicting extubation success in critically ill patients stratified by BMI: A prospective multicentre study

Background: The transition from Invasive mechanical ventilation (IMV) to spontaneous breathing, known as the weaning-process (WP), requires careful evaluation. In obese patients, WP may be compromised due to altered respiratory mechanics, increasing the risk of weaning failure. Objective: to evaluate the predictive capacity of objective cough measurement (OCM), spontaneous breathing trial (SBT), and diaphragmatic contraction velocity (DCV) in predicting WP success in obese patients. Methods: A prospective, multicenter cohort study was conducted in critically ill patients requiring IMV who were undergoing the extubation process. The predictive ability of SBT, DCV, and OCM for determining SBT and extubation success was evaluated. The analysis was stratified by body mass index (BMI <30 kg/m² vs. ≥30 kg/m²) to assess predictive performance across different weight categories. Results: A total of 367 patients were included, of whom 70 % (279/367) had a BMI <30 kg/m². OCM and DCV showed an AUC-ROC of 0.49 (95 % CI: 0.39–0.60) and 0.50 (95 % CI: 0.40–0.60) in the BMI <30 kg/m² and ≥30 kg/m² groups for predicting success in the SBT, respectively (p = 0.9510). The SBT showed an AUC-ROC of 0.83 (95 % CI: 0.70–0.98) and 0.87 (95 % CI: 0.82–0.92) in the BMI <30 kg/m² and ≥30 kg/m² groups for predicting successful extubation, respectively (p = 0.252). The SBT and DCV showed an AUC-ROC of 0.86 (95 % CI: 0.80–0.92) and 0.74 (95 % CI: 0.61–0.87) in the BMI <30 kg/m² and ≥30 kg/m² groups for predicting successful extubation, respectively (p = 0.113). The SBT and OCM showed an AUC-ROC of 0.90 (95 % CI: 0.86–0.94) and 0.85 (95 % CI: 0.77–0.93) in the BMI <30 kg/m² and ≥30 kg/m² groups for predicting successful extubation, respectively (p = 0.243). Conclusion: The SBT demonstrated the highest predictive accuracy for successful extubation across BMI groups, while OCM and DCV had limited predictive value. No significant differences were observed between BMI categories.