Fiberoptic sensor for noninvasive measurement of variceal pressure
Bibliographic record
Abstract
We present a new measuring probe based on a miniature fiberoptic pressure sensor that can measure esophageal variceal pressure. The probe consists of an outer flexible chamber filled with a pressure transmission medium, at the center of which is positioned the fibreoptic sensor with diameter of 0.5 mm (FOP-F125, FISO Technologies Inc., Quebec, Canada) ([ Fig. 1 ]). The single-column, flexible chamber has a 0.03-mm wall thickness and the chamber wall is made of polyurethane. The sensor within the medium is attached at one end to a connecting rod. When the membrane on the sensor chip is exposed to a rise in pressure in the surrounding medium, the light returning to the control unit is altered in accordance with the pressure deformations of the membrane and the altered interference conditions inside the cavity of the sensor [ 1 ]. The analog signals from sensor are transferred to both digital and analog values in the control unit and recorded with PC-based real-time data-acquisition hardware ([ Fig. 2 ], [ Fig. 3 ]). Fig. 1 Schematic of the novel pressure probe. 1: the flexible chamber with the pressure transmission medium inside it; 2: the fibreoptic sensor; and 3: the optical fiber. Fig. 2 Schematic of the fiberoptic variceal pressure measuring system. A/D, analog-to-digital; PC, personal computer. Fig. 3 The tracing on the PC monitor represents variceal pressure. We used the new probe in three patients with cirrhosis after gaining approval from our institutional review board. Portal–azygous disconnection was carried out after measurement of the variceal pressure, and portal vein pressure was measured (model 90308-11-14, Space Labs Inc., Issaquah, Washington, USA) in the initial stages of surgery by directly catheterizing the right gastroepiploic vein with a PE-16 catheter. The variceal and portal vein pressure recordings in the three patients were 22 mm Hg and 22.5 mm Hg, 18.5 mm Hg and 19 mm Hg, and 20 mm Hg and 20 mm Hg, respectively. Compared with conventional technology used to measure variceal pressure [ 2 ] [ 3 ] [ 4 ] [ 5 ], it is much easier to place the new probe (diameter 2 mm) into the correct position in relation to the varices through the endoscopic biopsy channel ([ Fig. 4 ]). We believe the new sensor can help determine variceal pressure in routine endoscopic examinations safely and effectively. Fig. 4 The probe is gently placed onto the esophageal varix under direct visual control to measure the variceal pressure. Endoscopy_UCTN_Code_TTT_1AO_2AM
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".