Characterizing Respiratory Mechanics in Lymphangioleiomyomatosis as Measured by Oscillometry
Bibliographic record
Abstract
Rationale: Lymphangioleiomyomatosis (LAM) is a rare cystic lung disease almost exclusively affecting women presenting as progressive pulmonary function loss and, in some instances, leading to respiratory failure.Approximately 70% of patients have abnormal lung function with the most common being airflow obstruction at presentation and decreased diffusing capacity (DLCO).Recent reports show a 3-4-fold decrease in the number of small airways in LAM lungs.Oscillometry, a non-invasive rapid pulmonary function test (PFT), is particularly sensitive to changes in respiratory mechanics in the lung periphery.The objective of the current study is to characterize oscillometry measurements in LAM patients, which has not been previously described, and to determine whether parameters derived from standard and intrabreath oscillometry correlate with disease severity.Methods: All LAM patients, diagnosed according to ATS guidelines and followed at the Rare Diseases Clinic at our institutions, were enrolled for sequential oscillometry and conventional PFTs at UHN and Montreal PFT Laboratories.Oscillometry, including the novel intrabreath tracking at 10 Hz was performed using the tremoflo® device (Thorasys Inc., Montreal, QC).Results: From August 2019 to December 2020, we enrolled 25 LAM patients (age=47.2±12.6 years; 24F/1M; 19 at UHN, 6 at McGill).Forced spirometry and single-breath technique, reported as mean ± SD, revealed mild airflow obstruction and decreased DLCO (%FEV1=78.6±24.8,%FVC=96.8±19,FEV 1 /FVC=0.67±0.15;%DLCO=70.1±25.2) with normal lung volumes by plethysmography (%RV=121±38.2,%TLC=99.5±23.2,%RV/TLC=105 ± 29.1).In contrast, oscillometry metrics were all worse than predicted normals for the cohort (Table 1), with higher resistance at 5 Hz (R5), frequency dependence of resistance (R5-19 or difference of resistance between 5 and 19 Hz) and AX (area of reactance) to suggest peripheral airway obstruction and ventilatory inhomogeneity.Intrabreath tracking, reported as median (IQR), reveal minimal tidal changes between endexpiration and end-inspiration in both resistance (ReE-ReI) and reactance (XeE-XeI): ReE-ReI=0.5 (0.8) cmH 2 O.s/L; XeE-XeI=0.1 (0.2) cmH 2 O.s/L.However, the area of reactance-vs-volume loop area (AXV) in the LAM patients [AXV= 0.44 (0.45) cmH 2 O.s] is two times higher than that reported in normal subjects.Conclusion: Data from this small cross-sectional cohort suggests that subtle physiologic abnormalities in LAM patients may be more sensitively assessed with oscillometry than with conventional pulmonary function tests.The increased AXV suggests development of expiratory flow limitation during normal breathing, which is associated with elevated resistance values.Increase in LAM patient recruitment and longitudinal follow-up will facilitate in determining whether oscillometry can accurately assess disease progression.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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".