Patients with prolonged mechanical ventilation (PMV) frequently experience impaired ventilation distribution, respiratory muscle dysfunction, secretion retention, and delayed liberation from mechanical ventilation. Electrical impedance tomography (EIT) provides real-time bedside visualization of regional ventilation and enables individualized respiratory physiotherapy strategies.

This multicenter randomized controlled trial aims to evaluate whether EIT-guided respiratory physiotherapy improves ventilator-free days at day 28 compared with conventional respiratory physiotherapy in adult patients with PMV.

Respiratory physiotherapy consists of airway clearance, chest physiotherapy techniques, breathing pattern optimization, and therapeutic positioning. In the EIT-guided group, real-time EIT imaging is used to individualize physiotherapy strategies based on predefined ventilation distribution indicators, while the control group receives standardized physiotherapy according to institutional protocols without EIT guidance.

Secondary outcomes include successful liberation from mechanical ventilation, diaphragm ultrasound parameters, EIT-derived ventilation distribution indices (exploratory mechanistic outcomes), ICU Mobility Scale, healthcare resource utilization, and safety outcomes.

This multicenter randomized controlled trial evaluates the effectiveness of electrical impedance tomography (EIT)-guided respiratory physiotherapy compared with conventional respiratory physiotherapy in adult patients with prolonged mechanical ventilation (PMV).

Eligible patients receiving invasive mechanical ventilation for at least 21 consecutive days will be randomly assigned in a 1:1 ratio to either the EIT-guided group or the control group, in addition to standard ICU care.

Respiratory physiotherapy consists of airway clearance, chest physiotherapy techniques, breathing pattern optimization, and therapeutic positioning. Both groups will receive standardized physiotherapy protocols with comparable treatment frequency and duration.

In the EIT-guided group, real-time EIT imaging will be used during each physiotherapy session. The control group will receive the same standardized physiotherapy components according to institutional protocols without EIT guidance.

The primary outcome is ventilator-free days at day 28 (VFD-28), defined as the number of days alive and free from invasive mechanical ventilation during the first 28 days after randomization. Patients who die before day 28 or remain invasively ventilated at day 28 will be assigned a value of zero. Reintubation within 72 hours will be considered treatment failure according to the predefined protocol.

Secondary outcomes include successful liberation from invasive mechanical ventilation by day 28, diaphragm ultrasound parameters, EIT-derived ventilation distribution indices (exploratory mechanistic outcomes), ICU Mobility Scale (IMS), healthcare resource utilization, and safety outcomes.

EIT-derived parameters are included as exploratory mechanistic outcomes to characterize physiological responses to the intervention and are not used for primary outcome adjudication.

Inclusion Criteria:

• Age ≥ 18 years.
• Invasive mechanical ventilation for ≥ 21 consecutive days.
• Clinically stable and eligible for respiratory physiotherapy as determined by the treating team.
• Expected to remain on invasive mechanical ventilation for at least 48 hours after enrollment.
• Written informed consent obtained from the patient or legally authorized representative.

Exclusion Criteria:

• Contraindications to electrical impedance tomography .
• Hemodynamic instability requiring high-dose vasoactive support.
• Severe hypoxemia refractory to optimization.
• Unstable fractures or other contraindications to mobilization or positioning.
• Pregnancy.
• Expected death within 48 hours.