Influence of ventilatory settings on pendelluft and expiratory muscle activity in hypoxemic patients resuming spontaneous breathing
Bibliographic record
Abstract
Pendelluft and expiratory muscle activity during spontaneous breathing should be minimized to reduce potential harmful effects. This study aimed to describe pendelluft and expiratory muscle activity in hypoxemic patients recovering spontaneous breathing after ≥ 72 h of lung-protective, fully controlled mechanical ventilation (MV) and assess the effect of pressure support ventilation (PSV) and positive end-expiratory pressure (PEEP). A physiological, randomized crossover study was conducted in hypoxemic patients receiving three levels of PSV: 5, 10, and 15 cmH₂O, and two PEEP levels: based on electrical impedance tomography before spontaneous breathing (PEEP EIT ) or according to PEEP-FiO 2 tables (PEEP ARDS ). Pendelluft was defined as the percentage of volume displaced from non-dependent to dependent lung regions during inspiration. Expiratory muscle activity was assessed by the expiratory rise in gastric pressure (ΔPga EXP ), and inspiratory effort was estimated using muscular pressure (Pmus). Statistical analyses included linear mixed-effects models and mediation analyses. Fifteen patients were enrolled (mean PaO 2 /FiO 2 ratio: 262 ± 51 mmHg; median duration of MV: 9 [5–13] days; 6 females). PEEP EIT was 11 [10–13] cmH₂O and PEEP ARDS 6 [5–7] cmH₂O. Expiratory muscle activity was observed in 13 patients. Compared to PS 5 cmH 2 O, PS to 10 and 15 cmH 2 O, adjusted for PEEP, significantly reduced both pendelluft and ΔPga EXP ( p < 0.001). When adjusted for PS, PEEP EIT was associated with a slight reduction in pendelluft ( p = 0.039) but a concomitant increase in ΔPga EXP ( p = 0.007) compared to PEEP ARDS . The mediation analysis revealed a significant negative mediating effect of ΔPga EXP on the relationship between PEEP EIT and pendelluft ( p < 0.001). Pmus, which was also significantly associated with pendelluft magnitude ( p < 0.001), mediated the effect of PS on reducing pendelluft ( p = 0.048), but not that of PEEP ( p = 0.46). In patients with ARDS transitioning to spontaneous breathing, increasing PS reduces pendelluft and expiratory muscle activity. Higher PEEP can decrease pendelluft, but its effect can be counteracted by increased expiratory activity.
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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 | 0.001 | 0.002 |
| 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".