Low postoperative hematocrit increases cerebrovascular damage after hypothermic circulatory arrest
Bibliographic record
Abstract
OBJECTIVE: The objective of this study was to evaluate the systemic and cerebral effects of different postoperative hematocrit management following cardiopulmonary bypass and deep hypothermic circulatory arrest. DESIGN: Animal case study. SETTING: Laboratory. SUBJECTS: Four-week-old Yorkshire piglets. INTERVENTIONS: Twelve piglets were subjected to cardiopulmonary bypass (hematocrit = 25%) and 100 mins of deep hypothermic circulatory arrest (15 degrees C). After weaning cardiopulmonary bypass, they were randomized to either group L or H, in which the postoperative hematocrit was maintained approximately 20% vs. approximately 30%, respectively, and survived for 6 hrs. MEASUREMENTS AND MAIN RESULTS: Changes in body weight, bioimpedance, and colloid oncotic pressure were assessed. Near-infrared spectroscopy and immunohistochemical assays for cerebral transforming growth factor-beta(1) and caspase-3 were performed. Postoperative weight gain (kg) and decreases in bioimpedance (ohms) were significantly less in group H (1.5 +/- 0.2 [H] vs. 2.4 +/- 0.6 [L], p = .01; 39.3 +/- 15.5 [H] vs. 89.1 +/- 29.6 [L], p = .01). Mean colloid oncotic pressure (mm Hg) was significantly higher in group H (10.8 +/- 1.6 [H] vs. 8.2 +/- 0.8 [L], p = .01) at 6 hrs postoperatively. Oxyhemoglobin, oxidized cytochrome aa(3) (muM x differential path-length factor), and tissue oxygenation index (%) were significantly better in group H (65.7 +/- 31.8 [H] vs. -104.7 +/- 55.2 [L], p = .0001; 0.52 +/- 4.1 [H] vs. -12.8 +/- 6.1 [L], p = .0001, and 55.7 +/- 4.6% [H] vs. 45.3 +/- 6.4% [L], p = .004, respectively). Cerebral transforming growth factor-beta(1) and caspase-3 scores were significantly better in group H (3.0 +/- 0.6 [H] vs. 1.9 +/- 0.9 [L], p = .04 and 1.8 +/- 0.5 [H] vs. 3.2 +/- 0.8 [L], p = .02, respectively). Mean arterial pressure (mm Hg) was consistently higher with group H (94.7 +/- 13.0 [H] vs. 78.3 +/- 11.5 [L], p = .003) despite comparable central venous pressure ( approximately 11 mm Hg). CONCLUSIONS: Lower postoperative hematocrit was associated with increased fluid retention, lower perfusion pressure, and worse cerebrovascular injury following deep hypothermic circulatory arrest. Postoperative hematocrit management may have profound systemic and cerebral effects after deep hypothermic circulatory arrest and merits further investigation.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 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) | 0.001 | 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".