Tensile Strength of 19- and 20-Gauge Arrow Epidural Catheters
Bibliographic record
Abstract
UNLABELLED: There are no data about the mechanical properties of the 20-gauge reinforced Arrow epidural catheter, which has a similar design to the 19-gauge reinforced Arrow catheter. In this study, we compared the mechanical properties of 19- and 20-gauge Arrow epidural catheters at 22 degrees C and 37 degrees C. The distal 12 cm of each catheter was suspended in an enclosed chamber maintained at either 22 degrees C or 37 degrees C. A pair of forceps was applied to each catheter 5 cm from the distal end (fixed site). Another pair of forceps was applied 15 cm from the catheter tip (traction site). The catheter was pulled. At 22 degrees C, the mean fracture force was 2.24 kg (range, 1.96 - 2.41 kg) for 5 19-gauge catheters and 2.17 kg (range, 2.04-2.41 kg) for 5 20-gauge catheters. At 37 degrees C, the mean force was 1.98 kg (range 1.84- 2.15 kg) for 5 19-gauge catheters and 1.99 kg (range, 1.81-2.09 kg) for 5 20-gauge catheters. There were no significant differences in tensile strength between the two different gauge catheters at either temperature. All the 19-gauge catheters fractured at the same "fixed site" at both temperatures. All the 20-gauge catheters elongated at the "fixed site" but fractured at the "traction site." We conclude that using the smaller-gauge catheter (20-gauge) is not associated with a more frequent rate of fracture. IMPLICATIONS: The 20-gauge Arrow epidural catheters had similar tensile strengths as the 19-gauge epidural catheters but fractured at the traction site rather than at the fixed site. Thus, the 20-gauge Arrow catheter may be a reasonable alternative to the 19-gauge Arrow catheter.
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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 | 0.002 | 0.006 |
| 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 | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".