Central venous catheter sampling of low molecular heparin levels
Bibliographic record
Abstract
BACKGROUND: The low molecular weight heparin effect in children is monitored using the anti-factor Xa level. Venipuncture is recommended; however, central venous catheter blood sampling is often necessary. Heparin infused through central venous catheters may contaminate central venous catheter blood samples, preventing reliable anti-factor Xa level measurement. Simultaneous anti-factor Xa/partial thromboplastin time measurement with central venous catheter blood sampling may predict anti-factor Xa reliability. OBJECTIVES: To determine the prevalence of heparin contamination as measured by the partial thromboplastin time/anti-factor Xa in central venous catheter blood samples and whether careful sampling could minimize heparin contamination of anti-factor Xa levels from central venous catheter blood sampling. METHODS: Simultaneous partial thromboplastin time/anti-factor Xa measurements from central venous catheter blood sampling determined the prevalence of heparin contamination of central venous catheter blood samples. In phase II, children receiving low molecular weight heparin had routine central venous catheter blood sampling to measure the peak anti-factor Xa and the simultaneous partial thromboplastin time. Anti-factor Xa levels with a partial thromboplastin time of >40 secs (pair 1) were identified; there was no low molecular weight heparin dose change, and the paired sample was repeated using a careful sampling technique (pair 2). Pairs 1 and 2 were compared to determine the efficiency of the sampling technique in removing heparin from the central venous catheter blood samples. RESULTS: In phase I, 100 children had 485 paired anti-factor Xa/partial thromboplastin time central venous catheter blood samples with 29% ± 4.1% (95% confidence interval 25% to 33%) anti-factor Xa with partial thromboplastin times of >40 secs. In phase II, 43 children had 129 paired anti-factor Xa/partial thromboplastin time samples with partial thromboplastin times of >40 secs. The pair 1 mean partial thromboplastin times/anti-factor Xa levels were 109.8 secs (SD 53.1, range 34.0 to >200 secs) and 1.03 units/mL (SD 0.56, range 0.26-4.2 units/mL). Repeated partial thromboplastin times/anti-factor Xa levels (pair 2) were significantly decreased from those of pair 1 (p < .001) with means of 58.5 secs (SD 21.2, range 22-152 secs) vs. 109.8 secs (SD 53.1, range 34.0 to > 200 secs, p < .001) and 0.63 unit/mL (SD 0.30, range 0.02-1.77 units/mL) vs. 1.03 units/mL (SD 0.56, range 0.26-4.2 units/mL), respectively. CONCLUSIONS: Measurement of the partial thromboplastin time performed in combination with that of the anti-factor Xa level can be used to assist health practitioners to identify unfractionated heparin contamination of anti-factor Xa levels drawn from central venous catheters. A careful sampling technique may minimize heparin contamination in central venous catheter blood samples.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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 teacher head, 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".