Lumbar Dural Sac Dimensions Determined by Ultrasound Helps Predict Sensory Block Extent During Combined Spinal-Epidural Analgesia for Labor
Bibliographic record
Abstract
BACKGROUND AND OBJECTIVES: The lumbosacral cerebrospinal fluid volume is a major determinant of the intrathecal spread of local anesthetics. Ultrasound imaging of the lumbar spine allows measurement of dural sac dimensions, which may potentially be used as a surrogate of cerebrospinal fluid volume. The purpose of this study was to investigate the correlation between lumbar dural sac diameter, dural sac length (DSL), and dural sac volume (DSV), measured by ultrasound, and the intrathecal spread of isobaric bupivacaine during combined spinal-epidural (CSE) analgesia for labor. METHODS: We examined 41 women with singleton pregnancies requesting neuraxial analgesia for labor. Using a 5-2-MHz curved-array ultrasound probe in the paramedian sagittal plane, we measured the dural sac width at each lumbar interspace and the DSL from L1-2 to L5-S1 interspace and calculated the dural sac volume (DSV). Following CSE block with 0.25% isobaric bupivacaine 1.75 mg and fentanyl 15 μg, peak sensory levels (PSLs) were recorded using ice, cotton, and pinprick. Statistical correlation coefficients between dural sac dimensions and PSLs were assessed by Spearman rank correlation. In addition, multiple linear regression models were used to select important predictors of PSLs. RESULTS: There was a moderate correlation between DSL and PSL to ice (ρ = -0.62; P < 0.0005) and to pinprick (ρ = -0.52; P = 0.017). Similarly, there was a moderate correlation between DSV and PSL to ice (ρ = -0.56; P = 0.004) and to pinprick (ρ = -0.61; P < 0.0008). Neither the DSL nor DSV correlated with PSL to cotton. Multiple linear regression analysis revealed that DSL, weight, and body mass index contributed to PSLs. CONCLUSIONS: The length of the lumbar spine determined by ultrasound, rather than the lumbar spine volume, combined with the weight or body mass index of the subject, is of particular value in predicting the intrathecal spread of isobaric bupivacaine during CSE analgesia for labor.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.005 |
| 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".