Results of an international survey (ISTH) on the management of therapeutic-intensity unfractionated heparin
Bibliographic record
Abstract
Introduction: Unfractionated heparin (UFH) remains the anticoagulant of choice for critically ill patients (parenteral administration, short-acting, readily reversible, low renal excretion). However, many key issues about laboratory monitoring and management are far from resolved. Initial dosing and adjustments are based on limited data. Close monitoring of UFH levels is mandatory, but there is still no consensus on the optimal approach. Furthermore, the therapeutic target is mostly based on experience, rather than on evidence. Method: Between November 2023 and February 2024, we conducted a cross-sectional online survey among International Society on Thrombosis and Haemostasis (ISTH) members involved in the management of patients receiving therapeutic-intensity UFH, under the aegis of the ISTH SSC Subcommittees on Control of Anticoagulation and Perioperative and Critical Care Thrombosis and Hemostasis. Our objective was to describe current practices and variations among centers, as reported by the respondents. Results: Of the 142 respondents from 15 countries around the world, 69% were physicians and 31% were laboratory medicine specialists. Therapeutic UFH was administered mainly for acute venous thromboembolism (n=74), mechanical circulatory support (n=74), mechanical heart valves (n=57), acute limb ischemia (n=54), atrial fibrillation (n=38), and acute coronary syndrome (n=37). Most respondents (85%) used citrate tubes to collect blood samples. UFH monitoring was based on an anti-Xa assay among 54% of respondents and on activated partial thromboplastin time (aPTT) among 46% of respondents, and on both for 2%. Different therapeutic ranges were used depending on local protocols and indications; the 0.3-0.7 IU/mL anti-Xa range was commonly used, except for patients on mechanical circulatory support with a lower range, mostly 0.3-0.5 IU/mL. Most respondents managed therapeutic UFH administration with weight-based dosing (88%), while fewer used a nomogram (57%) for dose adjustment. When a nomogram was used, it was primarily based on anti-Xa monitoring (86%). The situations when respondents administered antithrombin varied widely; 22% reported using it when antithrombin levels were below 60U/dL and 20% reported never using it. Conclusion: Our survey results revealed considerable heterogeneity in UFH management approaches, reflecting a knowledge gap and a paucity of evidence to guide decision-making. Key issues requiring well-designed up-to-date studies were identified, that include optimal approaches to heparin monitoring, assays and reagents to be used, therapeutic range based on indications, the use of weight-adjusted nomograms for initial dosing and titrating of UFH infusion, and indications for antithrombin supplementation. Our findings provide a strong rationale for the development of international guidance addressing these issues (under the aegis of professional societies including ISTH). Publication History Article published online: 13 February 2025 © 2025. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany
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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 | 0.004 | 0.009 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.002 | 0.003 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".