Accurate prediction of readiness to liberate patients from mechanical ventilation remains challenging. Conventional indices such as the rapid shallow breathing index (RSBI) and maximal inspiratory pressure (MIP) often miss early signs of injurious breathing patterns or regional ventilation asynchrony that can lead to extubation failure. Electrical impedance tomography (EIT) provides continuous, non-invasive imaging of regional lung ventilation. We developed a novel EIT-derived Flow Index (FI) which integrates the magnitude of inspiratory effort with the temporal synchrony of lung filling. This prospective, multicenter observational study aimed to (1) validate the predictive value of FI during spontaneous breathing trials (SBT) compared with conventional weaning indices, and (2) investigate the association between FI and pendelluft magnitude as a potential marker of patient self-inflicted lung injury (P-SILI).
This multicenter observational study was conducted in three ICUs in China. Adult patients (≥18 years) who received invasive mechanical ventilation for ≥48 hours and met standard criteria for SBT readiness underwent a standardized 30-minute pressure-support SBT (PSV 8 cmH₂O, PEEP 5 cmH₂O, FiO₂ ≤0.5). Continuous EIT recordings were performed to calculate global and regional FI from pixel-level inspiratory flow-time curves. Pendelluft magnitude was quantified as the percentage of intrapulmonary gas redistribution during inspiration. Conventional indices (RSBI, MIP, P0.1, NIF) and physiological variables were recorded. Primary Endpoint: SBT success (completion without respiratory distress, desaturation, or hemodynamic instability). Secondary Endpoints: * Reintubation within 48 h * Weaning failure * Ventilator-free days at day 7 * ICU mortality Predictive accuracy was evaluated via ROC analysis in training (n=90) and validation (n=60) cohorts.
Study Type
OBSERVATIONAL
Enrollment
150
Respiratory drive assessed by flow index measured by electrical impedance tomography.
Peking Union Medical College Hospital
Beijing, Beijing Municipality, China
Fujian Provincial Hospital
Fuzhou, Fujian, China
Department of Critical Care Medicine，Ruijin Hospital，Shanghai Jiao Tong University School of Medicine，Shanghai，China.
Shanghai, China
Spontaneous Breathing Trial (SBT) Success Rate
Proportion of patients who complete the 30-minute Spontaneous Breathing Trial (SBT) without signs of respiratory distress, desaturation, or hemodynamic instability.
Time frame: Within 30 minutes of Spontaneous Breathing Trial (SBT)
Reintubation Rate within 48 hours
Proportion of patients requiring reintubation within 48 hours following successful extubation.
Time frame: Within 48 hours after extubation.
Ventilator-Free Days by Day 7
Number of days free from mechanical ventilation within 7 days after extubation.
Time frame: Within 7 days after extubation.
ICU Mortality
Mortality rate of patients during their ICU stay in this study.
Time frame: during the ICU stay or within 24 hours following transfer out of the ICU
Correlation between FI and pendelluff magnitude
Pearson correlation coefficient between the Flow Index (FI) and pendelluff magnitude.
Time frame: During the 30-minute SBT.
Predictive value of FI vs. RSBI, MIP, P0.1 for SBT success
Comparison of the area under the ROC curve (AUC) for FI and conventional indices (RSBI, MIP, P0.1) in predicting SBT success.
Time frame: During the 30-minute SBT.
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