Agreement of IVC Diameter Measurements via Subcostal and Transhepatic POCUS Views
Bibliographic record
Abstract
Background: Inferior vena cava (IVC) point of care ultrasound (POCUS) is essential for hemodynamic evaluation, with the subcostal view (SCV) being the gold standard. However, in situations where this view is inaccessible, the transhepatic view (THV) is a viable alternative. This study evaluates the concordance between these two views in ventilated and non-ventilated patients, categorizing the IVC as small, intermediate, or large. Methods: This prospective observational study included 99 patients; healthy volunteers, ventilated patients, and non-ventilated patients. We measured end-expiratory IVC diameter, classified as small (<10 mm), intermediate (10-20 mm) or large (>20 mm), via SVC and THV. We then assessed agreement by categorical concordance, using Bland-Altman (mean bias ± 95% limits) and Pearson's correlation (r). Results: The overall concordance between both views was 83.8% (83/99; 95% CI: 76.4-90%). By IVC diameter category, concordance was 93.8% (15/16; 95% CI: 69.8-99.8) for small, 84% (42/50; 95% CI: 70-90 %) for intermediate, and 82% (27/33; 95% CI: 77-95%) for large. Concordance was unaffected by ventilation status (p = 0.83), but patients with Body Mass Index (BMI) ≥ 30 had lower concordance than those with BMI < 30 (73.9% vs. 89.5%; p = 0.086). The Bland-Altman analysis showed a mean bias of +0.22 mm with 95% limits of agreement from -6.99 to +7.43 mm. Pearson's correlation coefficient for the 99 paired measurements was r = 0.86 (p < 0.001), overall, and when stratified by category was r = 0.81 (small), r = 0.78 (intermediate) and r = 0.74 (large) (all p < 0.001). The sensitivity and specificity of THV for identifying "responders" (CI > 42%) were 28% and 93%, respectively. Conclusion: The THV is a reliable alternative for categorical evaluation of the IVC, particularly when the SCV is inaccessible. This method supports rapid and accurate clinical decision, especially for dichotomous POCUS decisions but should be used cautiously in patients with elevated BMI.
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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 | 0.009 | 0.030 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 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".