The goal of this single-center, pilot, randomized controlled trial is to evaluate the feasibility and preliminary efficacy of using the Flow Index (FI) to guide Pressure Support (PS) titration in adult patients receiving Pressure Support Ventilation (PSV) who are expected to require invasive mechanical ventilation for more than 48 hours. The main questions it aims to answer are: * Is FI-guided PS titration feasible and safe in a clinical ICU setting, as assessed by the proportion of failed safety assessments and the emergency termination rate? * Does FI-guided PS titration result in a greater proportion of data collection points with respiratory muscle pressure (Pmus) within the normal range (5-10 cmH₂O) compared to conventional PS titration based on tidal volume and respiratory rate? Researchers will compare the FI-guided PS titration group to the conventional PS titration group to see if FI-guided adjustment improves the proportion of assessments with adequate inspiratory effort (avoiding both excessive and insufficient support), and whether it leads to differences in clinical outcomes including duration of mechanical ventilation, extubation failure rate, tracheostomy rate, length of ICU and hospital stay, and in-hospital all-cause mortality. Participants will: * Be randomly assigned in a 1:1 ratio to receive either conventional PS titration (adjusting PS to achieve tidal volume of 6-8 mL/kg predicted body weight and respiratory rate of 20-30 breaths/min) or FI-guided PS titration (adjusting PS to maintain FI between 2.6 and 4.5) * Complete an intervention period with PS adjustments performed twice daily (at 8:00 AM and 8:00 PM) according to the assigned protocol * Have Pmus assessed at each data collection point to determine whether inspiratory effort falls within the target range * Undergo a 2-minute safety assessment after each PS adjustment to ensure adequate ventilation and avoid excessive airway pressures or respiratory distress * Be followed for up to 28 days after enrollment or until ICU discharge, with extended follow-up to hospital discharge or death for clinical outcome evaluation
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
60
Flow index (FI)-guided pressure support (PS) titration. FI is measured non-invasively from the ventilator flow waveform at the Y-piece using 10 consecutive stable breaths. PS is adjusted to maintain FI within 2.6-4.5: PS is reduced by 2 cmH₂O if FI \< 2.6, or increased by 2 cmH₂O if FI \> 4.5. After each adjustment, a 2-minute safety assessment verifies adequate ventilation (tidal volume 4-10 mL/kg predicted body weight, respiratory rate ≤35 breaths/min, peak inspiratory pressure ≤40 cmH₂O). PS titration is performed twice daily (8:00 AM and 8:00 PM) during the intervention period. All other ventilator settings follow standard care.
Patients receive PSV with PS titration based on tidal volume (VT) and respiratory rate (RR). PS is adjusted to achieve VT of 6-8 mL/kg predicted body weight and RR of 20-30 breaths/min: PS is reduced by 2 cmH₂O if VT \> 8 mL/kg and/or RR \< 20 breaths/min, or increased by 2 cmH₂O if VT \< 6 mL/kg and/or RR \> 30 breaths/min. If VT is within 6-8 mL/kg, PS is not adjusted and sedation/analgesia is optimized to achieve target RR. PS titration is performed twice daily (8:00 AM and 8:00 PM) during the intervention period.
Capital Medical University Beijing Tiantan Hospital
Beijing, Beijing Municipality, China
Proportion of assessments with Pmus in target range
The proportion of data collection points during the intervention period where respiratory muscle pressure (Pmus) falls within the predefined normal range of 5-10 cmH₂O, indicating adequate inspiratory effort.
Time frame: During the intervention period
Emergency termination rate
Proportion of participants requiring emergency termination of the intervention due to severe respiratory distress (SpO₂ \<90%), refractory arrhythmia or hypotension, disease progression requiring deep sedation, or frequent apnea alarms.
Time frame: Through study completion, up to 28 days
Safety assessment failure rate
Proportion of safety assessments that failed to meet predefined criteria after PS adjustment.
Time frame: During the intervention period
Incidence of adverse events
Occurrence of hypoxemia, respiratory distress, or barotrauma during the study period, recorded by type, timing, and relationship to the intervention.
Time frame: Through study completion, up to 28 days
Duration of invasive mechanical ventilation
Time from enrollment to successful extubation, measured in days.
Time frame: Through study completion, up to 28 days
Extubation failure rate
Proportion of participants who fail extubation and require reintubation within 48 hours after planned extubation.
Time frame: Through study completion, up to 28 days
Tracheostomy rate
Proportion of participants who undergo tracheostomy during the study period.
Time frame: Through study completion, up to 28 days
Length of ICU stay
Total duration of ICU admission from enrollment to ICU discharge or death, measured in days.
Time frame: Through study completion, up to 28 days
Length of hospital stay
Total duration of hospital admission from enrollment to hospital discharge or death, measured in days.
Time frame: Through study completion, up to 90 days
In-hospital all-cause mortality
Proportion of participants who die during the index hospitalization from any cause.
Time frame: Through study completion, up to 90 days
Total hospitalization cost
Total direct medical costs incurred during the index hospitalization, including ICU costs, mechanical ventilation-related expenses, medications, procedures, and diagnostic tests.
Time frame: From enrollment to hospital discharge or death, up to 90 days
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