Brain-based arterial pulse pressure threshold for death determination: a systematic review
Bibliographic record
Abstract
PURPOSE: There is lack of consensus regarding the minimum arterial pulse pressure required for confirming permanent cessation of circulation for death determination by circulatory criteria in organ donors. We assessed direct and indirect evidence supporting whether one should use an arterial pulse pressure of 0 mm Hg vs more than 0 (5, 10, 20, 40) mm Hg to confirm permanent cessation of circulation. SOURCE: We conducted this systematic review as part of a larger project to develop a clinical practice guideline for death determination by circulatory or neurologic criteria. We systematically searched Ovid MEDLINE, Ovid Embase, Cochrane Central Register of Controlled Trials (CENTRAL) via the Cochrane Library, and Web of Science for articles published from inception until August 2021. We included all types of peer-reviewed original research publications related to arterial pulse pressure as monitored by an indwelling arterial pressure transducer around circulatory arrest or determination of death with either direct context-specific (organ donation) or indirect (outside of organ donation context) data. PRINCIPAL FINDINGS: A total of 3,289 abstracts were identified and screened for eligibility. Fourteen studies were included; three from personal libraries. Five studies were of sufficient quality for inclusion in the evidence profile for the clinical practice guideline. One study measured cessation of cortical scalp electroencephalogram (EEG) activity after withdrawal of life-sustaining measures and showed that EEG activity fell below 2 μV when the pulse pressure reached 8 mm Hg. This indirect evidence suggests there is a possibility of persistent cerebral activity at arterial pulse pressures > 5 mm Hg. CONCLUSION: Indirect evidence suggests that clinicians may incorrectly diagnose death by circulatory criteria if they apply any arterial pulse pressure threshold of greater than 5 mm Hg. Moreover, there is insufficient evidence to determine that any pulse pressure threshold greater than 0 and less than 5 can safely determine circulatory death. STUDY REGISTRATION: PROSPERO (CRD42021275763); first submitted 28 August 2021.
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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 | 0.009 | 0.050 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.011 | 0.008 |
| Bibliometrics | 0.009 | 0.009 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.003 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.003 | 0.002 |
| Insufficient payload (model declined to judge) | 0.006 | 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 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".