TL;DR: 🔴 Harm signal, stopped early — lung-protective ventilation (low Vt, higher PEEP) in severe acute brain injury WORSENED mortality, ventilator dependency, and neurological outcome vs conventional ventilation.
1. Publication
- Title: Lung-Protective Mechanical Ventilation in Patients with Severe Acute Brain Injury: A Multicenter Randomized Clinical Trial (PROLABI)
- Acronym: PROLABI
- Year & Journal: American Journal of Respiratory and Critical Care Medicine, published September 17, 2024 (210(9):1123-1131)
- Citation: Mascia L, Fanelli V, Mistretta A, et al. Am J Respir Crit Care Med. 2024;210(9):1123-1131. doi:10.1164/rccm.202402-0375OC
2. Context & Rationale
Background: Lung-protective ventilation (low tidal volume, moderate-to-high PEEP) is standard ARDS practice, but had never been tested interventionally in acute brain injury (ABI) due to concerns that hypercapnia (from lower minute ventilation) and elevated PEEP could worsen intracranial pressure and cerebral hemodynamics.
Research Question/Hypothesis: In patients with severe ABI, does a lung-protective ventilatory strategy (lower Vt, higher PEEP) improve a composite of death, ventilator dependency, and ARDS at day 28, compared with conventional ventilation?
3. Design & Methods
- Study Type: Multicenter, open-label, controlled RCT
- Setting & Centers: Italy
- Population: 190 adults with severe acute brain injury
- Intervention: Lung-protective ventilation (lower Vt, higher PEEP)
- Comparator: Conventional ventilation
- Statistical Power & Follow-Up: Primary: composite of death, ventilator dependency, and ARDS at day 28. Trial terminated early.
4. Key Results
Stopped early. 190 patients randomized.
Outcome | Lung-Protective (Low Vt, Higher PEEP) | Conventional | Notes |
Composite: death, ventilator dependency, ARDS at day 28 (primary) | Not improved | — | Did not reduce the composite outcome |
Mortality | Higher | Lower | Worse with lung-protective strategy |
Ventilator dependency | More | Less | Worse with lung-protective strategy |
Long-term neurological outcome | Less favorable | More favorable | Worse with lung-protective strategy |
5. Internal Validity Assessment
Multicenter, open-label RCT, terminated early. Overall: Moderate — the early termination limits statistical power for definitive conclusions, but the internally consistent pattern of harm (worse mortality, ventilator dependency, AND neurological outcome, all in the same direction) strengthens confidence that this reflects a genuine signal rather than chance; independent commentary (Taming the SRU) explicitly describes this as the intervention group performing "worse" across multiple domains, "contrary to expectations."
6. External Validity Assessment
Italian, multicenter severe ABI population — relevant to similar acute brain injury populations, though single-country and modest final sample size (190, further limited by early termination) constrain generalizability of exact effect sizes.
7. Strengths & Limitations
Strengths: First interventional test of lung-protective ventilation specifically in ABI, addressing a genuine, long-standing clinical uncertainty; internally consistent harm signal across mortality, ventilator dependency, and neurological outcome domains.
Limitations: Terminated early, limiting power; open-label design; a subsequent letter to the editor raised concerns about baseline comorbidity data not being included.
8. Interpretation & Practice Impact
Does not support routine lung-protective ventilation (low Vt, higher PEEP) in severe ABI — the strategy that is standard-of-care in ARDS appears to cause harm in this specific population, likely via hypercapnia/PEEP effects on cerebral hemodynamics that this population is uniquely vulnerable to.
9. Controversies & Subsequent Evidence
A subsequent narrative review ("Novel approaches... reshaping mechanical ventilation in ABI") explicitly cites PROLABI alongside the VENTIBRAIN study as evidence that "excessively low tidal volumes or high PEEP may worsen outcomes in isolated ABI," highlighting the need for individualized "protective windows" rather than uniform ARDS-style lung-protective targets in this population. This contrasts with a prior systematic review of 8 observational studies (5639 patients) that had found no significant association between low-tidal-volume ventilation and short-term mortality in ABI — PROLABI's randomized (rather than observational) design provides a more definitive, if concerning, signal.
10. Summary & Executive Takeaway
Summary: PROLABI, terminated early, randomized 190 Italian patients with severe acute brain injury to lung-protective (lower Vt, higher PEEP) or conventional ventilation. The lung-protective strategy did not improve the composite primary outcome and was associated with higher mortality, more ventilator dependency, and less favorable long-term neurological outcomes.
Overall Takeaway: Contrary to the ARDS paradigm, applying lung-protective ventilation (low tidal volume, higher PEEP) in severe acute brain injury appears harmful rather than beneficial — a genuinely important, counterintuitive finding suggesting ventilation strategy in ABI requires population-specific "protective windows" rather than direct extrapolation from ARDS management principles.
11. Bibliography
- Robba C, et al. VENTIBRAIN study (referenced in subsequent reviews).
- Daza JF, et al. Low-Tidal-Volume Ventilation and Mortality in Patients With Acute Brain Injury: Secondary Analysis of an International Observational Study.