Reduction in Edema Cuff Size is not the Mechanism of Lung Protection Afforded by Airway Pressure Release Ventilation (APRV)
Bibliographic record
Abstract
Introduction We have shown that preemptive application of APRV significantly reduces the incidence of acute respiratory distress syndrome (ARDS). The exact protective mechanism is currently not known. Objective To determine if the mechanism of this protection was a reduction in the size of pulmonary vascular edema cuffing. Methods 14 swine were randomized into three groups: naïve (n=5), non‐protective ventilation (NPV; n=5), and airway pressure release ventilation (APRV; n=4). Naïve pigs did not receive lung injury. A fecal clot and gut ischemia/reperfusion‐induced ARDS model was used in both the NPV and APRV groups. Following injury, both groups were managed on their respective ventilator settings and sacrificed after 48 hours. Lung tissue was fixed and histology examined at 10× and 40× magnification. Lumen, tunica media, tunica adventitia, and lymphatics were identified, outlined, colored, and then quantified (). The following parameters were further evaluated for each vessel: lumen area, lumen roundness, tunica media area, tunica adventitia area, and lymphatic area. Clinical parameters and histologic lung injury scoring were analyzed. Results Vessel lumen roundness and tunica media area did not vary between groups (p>0.05). Lumen area was smaller in the injury groups (NPV/APRV) than in the naïve animals (p<0.05). The perivascular cuff, i.e. tunica adventitia and lymphatic vessels, was larger in the injured animals compared with naïve (p<0.05), without difference between ventilatory strategy. The tunica adventitia occupied a larger percent of total vessel area in the injured animals; however, lymphatics did not occupy a larger percent of the cuff compared with naïve, correlating instead with vessel size. Naïve pigs had lower wet/dry ratio compared with NPV pigs (5.47 vs. 8.82; p<0.05) without difference between Naïve and APRV groups (5.47 vs. 7.11, p>0.05) or APRV and NPV groups (7.11 vs 8.82; p>0.05). PaO 2 /FiO 2 ratio was higher in the APRV vs. NPV group (p<0.05), and histologic scoring showed decreased lung injury. Conclusion Despite increased lung protection using APRV, there was no difference in edema cuff size. Therefore, changes in edema cuff size do not contribute to APRV‐induced lung protection.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".