Comparison Of Non-clinical Tourniquet Research for Appliance Superiority & Tolerance (CONTRAST)
Bibliographic record
Abstract
BACKGROUND: Tourniquets are effective tools to manage life-threatening extremity hemorrhage. Commercial devices are recommended over improvised ones; however, mass casualty incidents and austere environments may prevent access to commercial devices. The aim of this review is to systematically search and meta-analyze commercial and improvised tourniquets: arterial occlusion, application speed, and patient tolerance. METHODS: We searched MEDLINE, Embase, CINAHL, Cochrane Library, SPORTDiscus, and ProQuest Dissertations & Theses Global using controlled terms; without date limits. Manikin, animal, and operative studies were excluded. Tourniquet devices were pooled by design and compared. Data regarding provider training and experience, recipient anthropometrics, application site, ease of application, speed, tolerance, and device efficacy were examined. RESULTS: 5169 studies were screened. The 36 included studies were prospective trials on healthy volunteers and published between 2000 and 2021. There were 8205 unique tourniquet applications to 1921 subjects using 23 unique commercial and improvised devices. Median sample size of included studies was 20 (IQR 26) participants, ranging from 1 to 773 participants; and 102 (IQR=152) applications ranging from 20 individual applications to 1546 unique applications. The most commonly assessed outcomes were: effectiveness (n=30), pain (n=18), speed of application (n=13), and amount of mechanical advantage (ex. Windlass turns) required (n=13). Male participants outnumbered females 1,414 to 169, mean age ranged from 21 to 45 years of age. Devices were pooled into 5 categories according to mechanical advantage mechanism: elastic, friction, mechanical, pneumatic, and windlass. Initial hemostasis was achieved in 95% of upper extremity placements (CI=0.89-0.98, p= 0.02), and 88% of mid-thigh applications (CI=0.78-0.94, p>0.01), in both groups pneumatic and mechanical tourniquet devices had the highest rates of success, with friction and elastic devices having the lowest rates of success. Meta-analysis showed that mechanical and pneumatic advantage systems had superior rates of hemostasis, ease of use, and pain tolerance scores. Due to study heterogeneity, we could not determine which devices were the fastest to apply. The overall risk of bias assessment for included studies found the certainty of studies ranged from moderate to critical. CONCLUSION: In pre-clinical studies mechanical and pneumatic advantage systems appear to be the superior tourniquet design. Due to the low certainty of evidence and non-randomizable nature of traumatic injury, pre-clinical tourniquet devices will likely continue to be tested on well volunteers. Adoption of a minimum data set, agreed upon definitions for testable metrics, and a standardized experimental design could improve the comparability and quality of future tourniquet device studies.
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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 | 0.025 | 0.078 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.013 | 0.022 |
| Bibliometrics | 0.009 | 0.008 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.005 | 0.003 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.009 | 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".