Air-bubble Method of Locking Central-vein Catheters: A Pilot Study
Bibliographic record
Abstract
The major source of catheter-associated bacteremia is contamination of the catheter hub during connection-disconnection procedures. Between dialyses, the catheter lumens are commonly locked with heparin (H), which does not prevent bacterial growth. Prophylactic use of antibiotics mixed with H reduces bacteremic episodes, but risks the development of antibiotic-resistant strains of bacteria. A new method of catheter locking has been developed (U.S. Patent 6,423,050), wherein anticoagulant is injected first, followed by 0.1 ml air bubble, and a bactericidal solution. The anticoagulant is then located at the catheter tip, where clotting is a problem, and the bactericidal solution is located at the catheter hub, where bacterial contamination is common. The air bubble prevents mixing of the two solutions. A feasibility study has been conducted using H 5,000 units/ml as the anticoagulant, and acidified (pH = 2.0) concentrated (27%) NaCl (ACS) as the bactericidal solution (Twardowski ZJ and Moore HL. Bactericidal properties of acidified (pH 2.0), concentrated (27%) NaCl (ACS), a potentially useful agent for locking hemodialysis catheters. Hemodial Int. Abstracts, 2003; 7: this issue). Ten patients were randomized, either to H lock (5 patients, 62 treatments) or air-bubble method (5 patients, 56 treatments). In the control group the catheters were locked with H according to the capacity provided by the manufacturer with 0.1 ml overfill. In the experimental group, the catheters were locked with H (amount varied according to catheter fill volume), 0.1 ml air bubble, and 0.9 ml ACS. Altogether, the lumen was overfilled by 0.1 ml. According to calculations, an incidental, rapid injection of 0.1 ml air is harmless and rapid injection of up to 1.5 ml of ACS would not perceptibly affect blood pH and/or osmolality in the superior vena cava. The study was approved by the Institutional Review Board of the University of Missouri. There were no problems with locking of the catheters. There were no episodes of bacteremia in either group, except for one case associated with purulent drainage from the exit and same organism in both cultures. In three instances in each group, the locking solution could not be aspirated and was injected without any subjective symptoms or objective signs. We conclude that the air-bubble method of locking central-vein catheters is safe, and a full-scale prospective randomized study is feasible.
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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 | 0.003 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.002 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.004 | 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".