Pressure Support Ventilation in Neurosurgical Patients: Can We Safely Reduce Assistance? Evaluation of Neurosurgical Patients' Ventilation Distribution - The ENVISION Study
Bibliographic record
Abstract
OBJECTIVES: To identify the prevalence of over-assistance from mechanical ventilation (MV) and to assess whether reducing MV support could be done safely in neurosurgical ICU patients in terms of risk of under-assistance and brain’s oxygenation. DESIGN: Prospective observation study. SETTING: Neurosurgical trauma ICU, Toronto, ON, Canada. PATIENTS: Twenty-seven brain-injured patients on MV having indication of a spontaneous breathing trial (SBT). INTERVENTIONS: Level of pressure support ventilation (PSV). MEASUREMENTS AND MAIN RESULTS: In neurosurgical patients, regional ventilation distribution using electrical impedance tomography, patient’s respiratory drive (airway occlusion at 100 ms [P0.1]), respiratory muscle pressure (Pmus), diaphragm and parasternal intercostal (PI) thickening fraction, brain oximetry, and electroencephalogram were assessed at clinical PSV (ClinPS), low PSV (LowPS, pressure support [PS] 5 cm H 2 O, positive end-expiratory pressure [PEEP] 5 cm H 2 O), SBT, PS 0 cm H 2 O, and PEEP 0 cm H 2 O. Over-assistance was defined by pressure muscle index less than 0 cm H 2 O; under-assistance was defined as Pmus greater than or equal to 15 cm H 2 O. Mixed effects models were used for analysis. Imbalanced dorsal/ventral distribution of ventilation improved by reducing assistance while respiratory effort increased. Over-assistance was present in ten cases (37%) during ClinPS and in none at LowPS and SBT; under-assistance was present in two, four, and seven cases at ClinPS, LowPS, and SBT. During SBT, compliance and end-expiratory lung volume decreased ( p < 0.0001). Brain activity did not vary. P0.1 greater than or equal to 4 cm H 2 O was associated with Pmus greater than or equal to 15 cm H 2 O with 80% sensitivity and 91% specificity during SBT. CONCLUSIONS: Neurosurgical patients seem to frequently be overassisted under PSV. Reducing the ventilatory support is often feasible and Pmus and P0.1 can help with detecting under-assistance.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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".