Hemodynamic effects of incremental lung hyperinflation
Bibliographic record
Abstract
Dynamic hyperinflation (DH) is common in chronic obstructive pulmonary disease and is associated with dyspnea and exercise intolerance. DH also has adverse cardiac effects, although the magnitude of DH and the mechanisms responsible for the hemodynamic impairment remain unclear. We hypothesized that incrementally increasing DH would systematically reduce left ventricular (LV) end-diastolic volume (LVEDV) and LV stroke volume (LVSV) because of direct ventricular interaction. Twenty-three healthy subjects (22 ± 2 yr) were exposed to varying degrees of expiratory loading to induce DH such that inspiratory capacity was decreased by 25%, 50%, 75%, and 100% (100% DH = inspiratory capacity of resting tidal volume plus inspiratory reserve volume ≈ 0.5 l). LV volumes, LV geometry, inferior vena cava collapsibility, and LV end-systolic wall stress were assessed by triplane echocardiography. 25% DH reduced LVEDV (-6 ± 5%) and LVSV (-9 ± 8%). 50% DH elicited a similar response in LVEDV (-6 ± 7%) and LVSV (-11 ± 10%) and was associated with significant septal flattening [31 ± 32% increase in the radius of septal curvature at end diastole (RSC-ED)]. 75% DH caused a larger reduction in LVEDV and LVSV (-9 ± 7% and -16 ± 10%, respectively) and RSC-ED (49 ± 70%). 100% DH caused the largest reduction in LVEDV and LVSV (-13 ± 9% and -18 ± 9%) and an increase in RSC-ED (56 ± 63%). Inferior vena cava collapsibility and LV afterload (LV end-systolic wall stress) were unchanged at all levels of DH. Modest DH (-0.6 ± 0.2 l inspiratory reserve volume) reduced LVSV because of reduced LVEDV, likely because of increased pulmonary vascular resistance. At higher levels of DH, direct ventricular interaction may be the primary cause of attenuated LVSV, as indicated by septal flattening because of a greater relative increase in right ventricular pressure and/or mediastinal constraint. NEW & NOTEWORTHY By systematically reducing inspiratory capacity during spontaneous breathing, we demonstrate that dynamic hyperinflation (DH) progressively reduces left ventricular (LV) end diastolic volume and LV stroke volume. Evidence of significant septal flattening suggests that direct ventricular interaction may be primarily responsible for the reduced LV stroke volume during DH. Hemodynamic impairment appears to occur at relatively lower levels of DH and may have important clinical implications for patients with chronic obstructive pulmonary disease.
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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".