Electrical Impedance Tomography-derived Flow Index During Spontaneous Breathing Trial Stratifies the Risk of Reintubation Within 48 h After Extubation

This multicenter observational study was conducted in three tertiary ICUs in China. Adult patients (≥18 years) receiving invasive mechanical ventilation for ≥48 hours and meeting readiness criteria underwent a standardized 30-minute pressure support SBT (PS 8 cmH₂O, PEEP 5 cmH₂O, FiO₂ ≤0.5) with continuous EIT monitoring. EFI was calculated breath by breath from the global impedance-time signal. Conventional weaning indices (RSBI, MIP, P0.1) and physiological variables were recorded.

Primary endpoint: SBT success (completion of 30-minute SBT without predefined failure criteria).

Key secondary endpoint: reintubation within 48 hours after extubation. Other secondary endpoints: ventilator-free days at day 7 (VFD-7), ICU mortality. Predictive performance was assessed using ROC analysis. The EFI cutoff value was derived from the primary endpoint analysis and carried forward for post-extubation risk stratification.

Inclusion criteria

• Age ≥18 years
• Acute respiratory failure requiring intubation and mechanical ventilation ≥48 hours
• Hemodynamic stability (no escalation of vasoactive agents)
• Oxygenation: FiO₂ ≤0.5, PEEP ≤8 cmH₂O
• Meeting standard ICU criteria for SBT readiness

Exclusion criteria

• Neuromuscular diseases impairing spontaneous breathing
• High cervical spinal cord injury
• Deep sedation (RASS ≤-3)
• Inadequate EIT signal quality
• Contraindications to EIT
• Pregnancy
• Expected survival <24 h