Neuroanesthesia & neurocritical care
The lower limit margin: a determinant of autoregulatory sensitivity to changes in cerebral perfusion pressure
Authors' conclusion
Our findings demonstrate that a narrow Lower Limit Margin is a marker of increased physiological vulnerability, associated with more frequent and severe CPP insults and worse neurological outcomes after TBI.
Study context
- Population
- Severe traumatic brain injury (TBI) patients receiving invasive multimodality monitoring
- Participants
- 234 patients
- Exposure
- Wider vs narrower Lower Limit Margin
- Outcome
- Unfavorable outcome (Glasgow Outcome Scale)
- Follow-up
- 6 months
Methodological detailsinvasive multimodality monitoring, causal mediation analysis, Minute-by-minute CPP, CPPopt and lower limit of autoregulation (LLA) derived using automated, validated methods
- Invasive multimodality monitoring
- Causal mediation analysis
- Minute-by-minute CPP, CPPopt and LLA derived using automated, validated methods
Main finding
As reported in the abstract
Unfavorable outcome (6-month Glasgow Outcome Scale) with wider Lower Limit Margin
OR for unfavorable outcome, wider Lower Limit Margin
0.59
CI 0.41–0.83p = 0.003
Observational data: associations, not effects.
Further findings
Time with CPP below LLA, wider Lower Limit Margin
- β (CI - 2.2 to - 1.9)
- - 2.1
Mediation by time below LLA
- Proportion of Lower Limit Margin effect on outcome mediated by time below LLA
- 58.9%
Interaction of Lower Limit Margin and short-term CPP variability
- Significant interaction: narrow margin plus high short-term CPP variability associated with worst outcomes and more time with CPP below LLA
Hourly short-term CPP variability exceeding ± 5 mmHg
- Proportion of hourly short-term CPP variability exceeding ± 5 mmHg
- Nearly 50%
Original publication
The lower limit margin: a determinant of autoregulatory sensitivity to changes in cerebral perfusion pressure. Crit Care. Published 27 October 2025. doi:10.
Composed by AI from the published abstract and checked against it. How Briefs are made →