Mechanical ventilation causes rapid diaphragm muscle atrophy, detectable within 18 hours of ventilator support, which is a major contributor to weaning failure and prolonged ICU stay.
This randomized controlled trial tests whether a physiotherapist-guided inspiratory endurance training program - achieved by progressively reducing pressure support (PS) levels on the ventilator - can preserve or improve inspiratory muscle strength and diaphragm structure in critically ill adults on mechanical ventilation, compared to standard ICU care.
Participants will be randomly assigned to one of two groups. The intervention group will receive twice-daily training sessions (weekdays only) in which the physiotherapist gradually reduces PS by up to 50% of the baseline level, causing the patient to breathe with greater muscular effort - equivalent to progressive endurance exercise for the diaphragm. The control group will receive standard weaning care as directed by the attending intensivist.
The primary outcome is maximal inspiratory pressure (PImax) at day 7. Secondary outcomes include diaphragm thickening fraction measured by ultrasound, time to successful extubation, weaning success rate, and mortality.
All measurements are performed by the ICU physician (blinded to group allocation) using airway occlusion maneuvers recorded on the ventilator and diaphragm ultrasound, following a standardized protocol.
Age ≥ 18 years
Admitted to ICU with invasive mechanical ventilation for more than 48 hours at the time of randomization
Expected to remain intubated for at least 24 additional hours, at the discretion of the attending intensivist
Active pressure support ventilation (PSV) mode with PS level ≥ 5 cmH2O
Neurological condition affecting central respiratory control (high cervical spinal cord injury, ALS, myasthenia gravis, active Guillain-Barré syndrome)
Established tracheostomy at the time of inclusion
Restriction on head-of-bed elevation to ≥ 30 degrees
Decision to limit therapeutic effort (LET) or life expectancy < 48 hours
Parallel
Progressive Pressure Support Reduction (IRT-PS)
BehavioralProgressive reduction of pressure support (PS) during ventilator-assisted breathing, performed by a physiotherapist twice daily (weekdays only). Sessions consist of 1-3 sets of 5-15 minutes with 2-minute rest intervals at baseline PS. PS is reduced by 25% initially up to a maximum of 50% of baseline (minimum 5 cmH2O) for PS ≥10 cmH2O; by 1-2 cmH2O for PS 5-9 cmH2O; and by 1 cmH2O down to 0 cmH2O for PS \<5 cmH2O. Target perceived exertion: Borg CR10 3-5. P0.1 monitored continuously; session stopped if P0.1 \>4 cmH2O sustained \>2 minutes (Goligher et al. criteria). Safety stop criteria: RR \>35 rpm, SpO2 \<90%, HR \>120 bpm.
Standard ICU Care
Other interventionConventional weaning managed by the attending intensivist according to standard clinical practice, without a structured inspiratory muscle training protocol. Conventional physiotherapy (early mobilization, chest physiotherapy) permitted in both groups.
Maximal Inspiratory Pressure (PImax)
Measured by manual airway occlusion at end-expiration with pressure curve recorded on the ventilator. Standardized verbal instruction given to the patient. Best of 3 valid maneuvers recorded. Performed by the ICU physician blinded to group allocation.
Diaphragm Thickening Fraction (DTF)
measured by ultrasound (linear probe 7-15 MHz, zone of apposition, M-mode, average of 3 cycles). Performed by ICU physician per standardized protocol.
P0.1 (Airway Occlusion Pressure at 100ms
respiratory drive indicator, read directly from ventilator display
Time to Successful Extubation
hours from randomization to extubation without reintubation within 48 hours
Weaning Success Rate
proportion of patients extubated without reintubation within 48 hours
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University of Santiago de Compostela
Lead sponsor
University of Vigo
Sponsor institution
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