Intracranial response to positive end-expiratory pressure is influenced by lung recruitability and gas distribution during mechanical ventilation in acute brain injury patients: a proof-of-concept physiological study
Bibliographic record
Abstract
BACKGROUND: The effect of positive end-expiratory pressure (PEEP) on intracranial pressure (ICP) dynamics in patients with acute brain injury (ABI) remains controversial. PEEP can benefit oxygenation by promoting alveolar recruitment, but its influence on ICP is complex. The primary aims of this study were to investigate 1) how lung recruitability influences oxygenation and 2) how lung recruitability and regional gas distribution, measured via recruitment-to-inflation (RI) ratio and electrical impedance tomography (EIT), affect ICP in response to PEEP changes in critically ill patients in their early phase of ABI. METHODS: O). Changes in ICP (ΔICP) were calculated between high and low PEEP. Lung inhomogeneity indices (global inhomogeneity index [GI] and local inhomogeneity index [LI]) were derived from EIT. Correlations between ventilatory variables and ICP were analysed. RESULTS: Blood oxygenation significantly decreased, going from high (14 [IQR: 12-15] cmH₂O) to low (4 [IQR: 2-5] cmH₂O) PEEP. Reducing PEEP significantly increased ICP (from 9 [IQR: 5-13] to 12 [IQR: 8-16] mmHg, p < 0.01), while cerebral perfusion pressure (CPP) improved (from 71 [IQR:67-83] to 75 [IQR: 70-84] mmHg, p = 0.03) and mean arterial pressure (MAP) increased (from 79 [IQR: 69-95] to 84 [IQR: 76-99] mmHg, p < 0.01). The RI ratio correlated significantly with ΔICP (rho = 0.87, p < 0.01), as did Vrec% (proportion of recruited volume, rho = 0.65) and GI (rho = 0.5). LI did not correlate with ΔICP. PRx was 0.30 [IQR: 0.12-0.42], indicating a deranged cerebral autoregulation. CONCLUSIONS: Patients with a higher potential for lung recruitability had a more beneficial effect of PEEP on oxygenation. These effects should be interpreted cautiously, given that lung recruitability and global inhomogeneity of gas distribution significantly influenced the intracranial response to PEEP in ABI patients. As indicated by MAP and CPP, PEEP may impact systemic haemodynamics and cerebral perfusion when cerebral autoregulation is deranged. These findings underscore the importance of multimodal (i.e. respiratory, cerebral and haemodynamics) monitoring for optimising ventilation strategies in ABI patients and provide a framework for future research. Trial registration Registration number: NCT05363085, Date of registration: May 2022.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".