The Effect of Prone Position-induced Lung Recruitment is Independent From Its Effect on Perfusion and Gas Exchange: A Secondary Computed Tomography Analysis of a Controlled Circulatory Death Donor Model
Bibliographic record
Abstract
Abstract RATIONALE: Prone position (PP) is recommended in patients with moderate-severe acute respiratory distress syndrome, as it improves oxygenation, decreases alveolar overdistension, improves lung recruitment, and reduces mortality. However, it has not been conclusively demonstrated whether the beneficial effect of PP-induced lung recruitment is independent from its effect on perfusion and gas-exchange. In an animal model of organ donation after controlled cardiac death (DCD) maintained non-ventilated and non-perfused for 3 hours of warm ischemic time (WIT), our group demonstrated that, after reperfusion in the ex-vivo lung perfusion platform in standard position, gas exchange, compliance and vascular resistance were better in lungs from pigs maintained in PP during WIT compared to those kept supine1.Whether these results depend on changes in alveolar recruitment in this model, which allows to separate the effect of PP on perfusion and gas-exchange from that on alveolar recruitment, has not been studied. METHODS: We analyzed the computed tomography scans (CT) performed in our previous DCD model investigation to compare the lung volume distribution overtime in supine and PP.In the original experiment, ten Yorkshire DCD pigs were randomly assigned to prone (n=5) or supine (n=5) position during 3 hours of WIT. After being ventilated in the assigned position for five minutes, the airway was clamped at peak pressure of 25 cmH2O to maintain lung inflation during WIT. C-arm cone-beam CT (Siemens Healthcare) was performed at the beginning (T0) and the end of WIT (T3) in 3 pigs in each group and analysed with the Mimics Medical 19 software (Materialise). Lung below the diaphragm were manually contoured and four lung compartments (non-aerated, poorly aerated, normally aerated and hyperinflated) were identified based on the distribution of Hounsfield Unit, using conventional thresholds. Lung tissue weight was expressed as percentage of total lung volume. RESULTS: At T0, in the PP the medians of normally aerated tissue and poorly aerated tissue were 93% (99-93) and 5% (4-7), compared to 65% (62-66) and 29% (28-33) in supine position (p<0.01). At T3, in the PP group the normally aerated and the poorly aerated tissue were 92% (90-92) and 6% (5-8), respectively, compared to 60% (58-60) and 36% (35-38) in the supine group (p<0.01-Figure1). DISCUSSION: PP resulted in higher alveolar recruitment during WIT with consequent better lung physiologic performance after reperfusion, indicating that the benefit of PP-induced alveolar recruitment is independent from its effect on perfusion and gas exchange.
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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 | 0.000 |
| 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 | 0.000 |
| 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".