Effect of Automated Closed-loop ventilation versus conventional Ventilation on duration and quality of ventilation in critically ill patients (ACTiVE)

Abstract

The MVENT trial is a multicentre, assessor-blinded, parallel-group pilot RCT designed to compare a “minimal ventilation” strategy—daily one-hour spontaneous breathing trials (SBT) with minimal pressure support or CPAP—versus usual care in critically ill adults mechanically ventilated for ≥24 hours. The hypothesis is that minimal support SBTs may better assess readiness for extubation, avoid over-assistance, and shorten ventilation duration. The pilot will assess feasibility (recruitment, protocol adherence, separation of ventilatory support) to inform a future definitive trial .

Key Points

1. Background and rationale – Prolonged invasive ventilation increases risk of complications such as ventilator-associated pneumonia, diaphragmatic weakness, and mortality. Conventional SBTs with higher pressure support may mask patient weakness and overestimate readiness for extubation; minimal support trials may more accurately reveal spontaneous breathing capacity .
2. Objective of the pilot – To determine the feasibility of conducting a large RCT comparing minimal support versus usual care SBTs, by assessing recruitment rates, protocol adherence, clinician acceptance, and separation in ventilator support levels between groups .
3. Study design – Randomised (1:1), parallel-group, multicentre, with allocation concealment and assessor blinding for primary outcome evaluation. Adult ICU patients ventilated ≥24h and meeting SBT screening criteria will be eligible .
4. Intervention – The “minimal ventilation” group will undergo daily one-hour SBTs using CPAP ≤2 cmH₂O and/or pressure support ≤5 cmH₂O, adjusted for endotracheal tube size. Usual care SBTs may use higher support per local practice .
5. Weaning and extubation – Extubation decisions will be made by treating clinicians based on SBT performance and clinical judgment; reintubation criteria and post-extubation respiratory support will follow standard protocols .
6. Primary outcome (pilot) – Feasibility, defined by recruitment of ≥80% of eligible patients, ≥80% adherence to assigned SBT protocol, and clear separation in ventilatory support during SBTs between groups .
7. Secondary outcomes – Clinical measures include ventilator-free days to day 28, ICU and hospital length of stay, extubation success at 48h and 7d, reintubation rates, and mortality at ICU discharge, hospital discharge, and day 90 .
8. Sample size and sites – Planned enrolment of 100 patients across 4–6 Canadian ICUs over 12 months; sample size chosen to estimate feasibility outcomes with precision, not powered for clinical endpoints .
9. Statistical plan – Descriptive analyses for feasibility metrics; exploratory comparisons of clinical outcomes using intention-to-treat. This will guide effect size estimation for the full trial .
10. Significance – If feasible, the definitive RCT could shift practice toward minimal support SBTs, potentially reducing ventilation time, diaphragm injury, and post-extubation respiratory failure .

Conclusion

The MVENT pilot will determine whether a pragmatic, low-assistance approach to SBTs is feasible in diverse ICU settings. Results will guide a larger RCT aimed at improving liberation strategies from mechanical ventilation in critically ill adults .

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Discussion Questions

1. Could minimal support SBTs increase early extubation failures compared to higher support trials, and how should this be balanced against potential benefits?
2. What are the most reliable physiologic markers during minimal support SBTs to predict extubation success?
3. How might diaphragm-protective ventilation principles be integrated into daily readiness assessments for liberation?

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