Brain Blood Flow in the Neurological Determination of Death: Canadian Expert Report
Bibliographic record
Abstract
The neurological determination of death (NDD, brain death) is principally a clinical evaluation. However, ancillary testing is required when there are factors confounding the clinical determination or when it is impossible to complete the minimum clinical criteria. At the time of the 2003 Canadian Forum clarifying the criteria for brain death, 4-vessel cerebral angiography or radionuclide angiography were the recommended tests and the electroencephalogram was no longer supported. At the request of practitioners in the field, the Canadian Council for Donation and Transplantation sponsored the assembly of neuroradiology and neurocritical care experts to make further recommendations regarding the use of ancillary testing. At minimum, patients referred for ancillary testing should be in a deep unresponsive coma with an established etiology, in the absence of reversible conditions accounting for the unresponsiveness and the clinical examination should be performed to the fullest extent possible. For newborns, children and adults, demonstration of the absence of brain blood flow by following recommended imaging techniques fulfill the criteria for ancillary testing: 1. radionuclide angiography or CT angiography 2. traditional 4-vessel angiography 3. Magnetic resonance angiography or Xenon CT. In the absence of neuroimaging, an established cardiac arrest, as defined by the permanent loss of circulation, fulfills the ancillary criteria for the absence of brain blood flow. Acknowledging the existing limitations in this field, further research validating current or evolving techniques of brain blood flow imaging are recommended.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.006 | 0.021 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.002 | 0.002 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.003 | 0.001 |
| Research integrity | 0.005 | 0.003 |
| Insufficient payload (model declined to judge) | 0.004 | 0.002 |
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 source (direct Gemma or distilled Codex), 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".