1,357,626 research outputs found
1-D freeze-thaw model code Rotem et al., 2023
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1-D freeze/thaw model code – copy and paste code rows into Python (Spider-Anaconda).
This Python-script describes the 1-D Heat transfer model code developed for the research first Rotem et al., (2023). The 1-D model is a transient one-dimensional heat transfer model suitable for simulating permafrost dynamics. The core of the model is an explicit forward-difference time approximation of the one-dimensional heat transfer equation. This script is tailored to simulate the Holocene ground temperature development in Adventdalen, Svalbard, but may be modified to fit other purposes.
#Usage must be cited by reference to Rotem et al. (2023).</p
Effect of acceleration forces during transport through a pneumatic tube system on ROTEM® analysis
No full textROTEM® is considered a helpful point-of-care device to monitor blood coagulation in emergency situations. Centrally performed analysis is desirable but rapid transport of blood samples is an important prerequisite. The effect of acceleration forces on sample transport through a pneumatic tube system on ROTEM® should be tested at each institution to exclude a pre-analytical influence. The aims of the present work were: (i) to investigate the effect of pneumatic tube transport on ROTEM® parameters; (ii) to compare blood sample transport via pneumatic tube vs. manual transportation; and (iii) to determine the effect of acceleration forces on ROTEM® parameters
Implementing and sustaining Point of Care ROTEM® into a trauma activation protocol for the management of patients with traumatic injury: A mixed-methods study
No full textBackground: Up to 40% of patients with traumatic injury experience critical bleeding, many requiring transfusion of blood products. International transfusion guidelines recommend the use of viscoelastic testing to guide blood product replacement. We implemented a Point of Care ROTEM® blood test for trauma patients who present and initiate a trauma activation. Objectives: The aim of this study was to undertake an evaluation of the implementation data to identify factors which helped and hindered this new practice. Methods: A sequential mixed-methods design was conducted to evaluate intervention implementation. The intervention was designed with interprofessional collaboration and incorporated education and skills training supplemented with a decision aide. Patients aged ≥ 18 years who met the trauma activation criteria were included. Data collection occurred throughout the 21-month implementation period inclusive of initial roll out, maintenance and sustainability and include the number of ROTEM® blood tests taken and clinical characteristics of patients. Individual interviews were conducted with health professionals with experience of the intervention after the implementation period was complete. Results: A total of 1570 eligible patients were included. The number of patients who had a ROTEM® blood test taken increased over time to 63%. The proportion of patients having a ROTEM® blood test obtained was higher for major trauma patients (n=162, 66.9%) who were admitted to the Intensive Care Unit. Regression analysis found trauma service presence on arrival and the sustainability phase of implementation increased the likelihood of having a ROTEM® taken. Qualitative data suggest that a more tailored approach to intervention implementation would assist with adoption. Conclusion: Implementation of new practice requires careful planning and should be undertaken with input from end-users. Continuous evaluation is necessary to support ongoing implementation and sustainability. To ensure effective implementation occurs, complex interventions need to be made workable and integrated in everyday health care practice.No Full Tex
Substitution of ROTEM FIBTEM A5 for A10 in trauma: an observational study building a case for more rapid analysis of coagulopathy
No full textPurpose: Rotational thromboelastometry (ROTEM®) allows guided blood product resuscitation to correct trauma-induced coagulopathy in bleeding trauma patients. FIBTEM amplitude at 10 min (A10) has been widely used to identify hypofibrinogenaemia; locally a threshold of < 11 mm has guided fibrinogen replacement. Amplitude at 5 min (A5) carries an inherent time advantage. The primary aim was to explore the relationship between FIBTEM A5 and A10 in a trauma. Secondary aim was to investigate the use of A5 as a surrogate for A10 within a fibrinogen-replacement algorithm. Methods: Retrospective observational cohort study of arrival ROTEM results from 1539 consecutive trauma patients at a Level 1 trauma centre in Australia. Consistency of agreement between FIBTEM A5 and A10 was assessed. A new fibrinogen replacement threshold was developed for A5 using the A5–A10 bias; this was clinically compared to the existing A10 threshold. Results: FIBTEM A5 displayed excellent consistency of agreement with A10. Intraclass correlation coefficient = 0.972 (95% confidence interval [CI] 0.969–0.974). Bias of A5 to A10 was − 1.49 (95% CI 1.43–1.56) mm. 19.34% patients met the original local threshold of A10 < 11 mm; 19.28% patients met the new, bias-adjusted threshold of A5 < 10 mm. Conclusion: ROTEM FIBTEM A5 reliably predicts A10 in trauma. This further validates use of the A5 result over A10 allowing faster decision-making in time-critical resuscitation of trauma patients. A modification of -1 to the A10 threshold might be appropriate for use with the A5 value in trauma patients.Full Tex
Comparison of thromboelastometry by ROTEM (R) Delta and ROTEM (R) Sigma in women with postpartum haemorrhage
No full textHaemostatic treatment in women experiencing postpartum haemorrhage is increasingly based on point-of-care devices such as ROTEM (R) thromboelastometry. Recently, a fully automated successor of the ROTEM (R) Delta device, the ROTEM (R) Sigma was introduced. To determine whether these devices provide similar results, we compared ROTEM (R) parameters using the ROTEM (R) Delta and Sigma devices in women experiencing postpartum haemorrhage. Prospective observational cohort study of 23 women experiencing postpartum haemorrhage. ROTEM (R) INTEM, EXTEM, FIBTEM and APTEM measurements handled by the ROTEM (R) Delta and Sigma devices were compared. ROTEM (R) FIBTEM values were also related to Clauss fibrinogen values. A correlation of Spearman's r (r(s)) varying between 0.76 and 0.95 was displayed between clot firmness measured in millimeters at 5 (A5), 10 (A10) and 20 (A20) minutes after start of clot formation measured by EXTEM, INTEM and APTEM assays executed on both devices; A5, A10 and A20 of FIBTEM correlated less well (r(s) between 0.71 and 0.74), especially after five and ten minutes. Correlation between both devices regarding clotting time (CT) was poor. The observed correlation between levels of Clauss fibrinogen and FIBTEM A5 was r(s) = 0.70, (95% confidence interval (CI): 0.38 to 0.87) for Delta and r(s) = 0.85, (CI 0.65 to 0.94) for Sigma. A5, A10 and A20 measured in EXTEM, INTEM and APTEM obtained from ROTEM (R) Delta and Sigma devices were similar. EXTEM, FIBTEM and APTEM CT values from both devices showed no correlation. Substantial variation was found between FIBTEM assays of the devices. Consequently, results of FIBTEM assays should always be interpreted in the context of device-specific reference values. Correlation with Clauss fibrinogen was better in the ROTEM (R) Sigma device.Clinical epidemiolog
First experience with a ROTEM-enhanced transfusion algorithm in patients undergoing aortic arch replacement with frozen elephant trunk technique. A theranostic approach to patient blood management
No full textStudy objective: To assess the effect of a rotational thromboelastometry (ROTEM)-enhanced transfusion algorithm with hemostatic agents on allogenic blood transfusion in patients undergoing frozen elephant trunk (FET) surgery. Design: Retrospective observational study conducted in a tertiary-care center. Setting: A tertiary care referral center for cardiac surgery. Patients: All patients undergoing elective FET were included in the study. Intervention: Until 2016, a protocol based on estimated blood losses and conventional coagulation tests was used. After, a ROTEM-enhanced transfusion protocol was adopted. Measurements: The transfusion rate of each blood component was observed and reported. Methods: Retrospective, observational study. Main results: Out of 40 consecutive patients, 19 underwent FET surgery with a conventional transfusion approach and 21 with a ROTEM-enhanced transfusion strategy. Considering the overall transfusion rate, the administration of fresh frozen plasma and platelets was significantly lower in the ROTEM compared to conventional group (1000 [0–2500] vs 0 [0–875] ml, p = 0.015 and 1 [1, 2] vs 0 [0–1], p = 0.016, respectively). ROTEM algorithm allowed to decrease the number of patients who required plasma and platelets transfusion of 31%. Furthermore, a 40% reduction in overall allogenic blood products was observed. Number of red blood cells administered, percentage of patients transfused with red blood cells, blood losses, reoperation for bleeding and mortality did not significantly differ between the two groups. At the multiple linear regression analysis only ROTEM algorithm was associated with a significant decrease in the number of plasma and platelets units administered intraoperatively, at 24 h, at the ICU discharge and overall. ROTEM algorithm allowed to save 1435 ml of plasma, 0.91 unit of platelets and overall transfusion cost of the 21% per patient. Conclusions: A ROTEM-enhanced transfusion strategy halved intraoperative transfusion in the setting of FET. Further studies are needed to confirm the magnitude of our findings on clinically relevant endpoints
Implementation of point-of-care ROTEM® into a trauma major haemorrhage protocol: A before and after study
No full textObjective: The aim of the present study was to assess transfusion practices with the implementation of a targeted viscoelastic haemostatic assay (VHA) (ROTEM®) guided coagulation management programme into a major haemorrhage protocol for trauma patients requiring ICU admission, starting from time of arrival in the ED. Methods: This retrospective observational study was conducted in a major trauma centre in Australia. One hundred and sixty-two trauma patients admitted to the ICU between January 2013 and December 2015 with an Injury Severity Score ≥12 and who received blood products were included: 37 in the pre-group, 48 during implementation and 77 in post-group. The primary outcome was blood and blood product administration amounts. Results: Packed red blood cell transfusion amounts did not significantly change post introduction of the ROTEM®. There was a significant increase in fibrinogen replacement between the pre- and post-groups (P < 0.001), accompanied by a reduction in the use of fresh frozen plasma (P < 0.001) and prothrombinex (P < 0.001). Platelet usage in the post-group was higher but not reaching statistical significance (P = 0.051). Post-implementation point-of-care ROTEM® testing was able to be performed in the ED in 94.8% of cases. Conclusion: Although there was no overall reduction of packed red blood cell usage, a change in the pattern of administration of other blood products was observed with the implementation of a targeted VHA (ROTEM®) guided coagulation management programme. Larger studies are needed to further define the role of early VHA testing to guide correction of trauma-induced coagulopathy and the effect on clinical outcomes
Revisiting the Uber Assumption in the Algebraic Group Model: Fine-Grained Bounds in Hidden-Order Groups and Improved Reductions in Bilinear Groups
No full textWe prove strong security guarantees for a wide array of computational and decisional problems, both in hidden-order groups and in bilinear groups, within the algebraic group model (AGM) of Fuchsbauer, Kiltz and Loss (CRYPTO '18). As our first contribution, we put forth a new fine-grained variant of the Uber family of assumptions in hidden-order groups. This family includes in particular the repeated squaring function of Rivest, Shamir and Wagner, which underlies their time-lock puzzle as well as the main known candidates for verifiable delay functions; and a computational variant of the generalized BBS problem, which underlies the timed commitments of Boneh and Naor (CRYPTO '00). We then provide two results within a variant of the AGM, which show that the hardness of solving problems in this family in a less-than-trivial number of steps is implied by well-studied assumptions. The first reduction may be applied in any group (and in particular, class groups), and is to the RSA assumption; and our second reduction is in RSA groups with a modulus which is the product of two safe primes, and is to the factoring assumption.
Additionally, we prove that the hardness of any computational problem in the Uber family of problems in bilinear groups is implied by the hardness of the q-discrete logarithm problem. The parameter q in our reduction is the maximal degree in which a variable appears in the polynomials which define the specific problem within the Uber family. This improves upon a recent result of Bauer, Fuchsbauer and Loss (CRYPTO '20), who obtained a similar implication but for a parameter q which is lower bounded by the maximal total degree of one of the above polynomials. We discuss the implications of this improvement to prominent group key-exchange protocols
Critical evaluation of a targeted point of care ROTEM guided coagulation and haemostasis management programme in severe trauma
No full textIntroduction: Rotational thromboelastrometry (ROTEM ®) is a point-of-care testing device that can be used to measure viscoelastic properties on multiple aspects of blood coagulation in trauma.No Full Tex
Introduction of a ROTEM protocol for the management of trauma-induced coagulopathy
No full textAims: Point-of-care viscoelastic tests such as rotational thrombelastometry (ROTEM) and thromboelastography (TEG) give rapid information on the kinetics of clot formation, clot strength and fibrinolysis. We developed a ROTEM algorithm for the management of trauma patients at risk of massive haemorrhage using either 5 or 10 minute EXTEM and FIBTEM ROTEM thresholds. Study aims were (a) to compare time to results for ROTEM testing versus laboratory conventional coagulation testing (CCT) and (b) to compare incidence of Trauma-induced coagulopathy (TIC) for our 5 and 10 minute ROTEM algorithms versus both the CCT-based European guideline algorithm and the ROTEM-based iTACTIC study algorithm, in both MT and non-MT patients. Methods: Single centre, prospective, observational Emergency Department based study. All trauma patients who underwent ROTEM testing were included. Data was collected from the ROTEM Sigma machine and hospital Electronic Patient Records and analysed. Results: Between April 2016 and May 2019, 57 trauma patients were enrolled. Mean age was 47.4 years (SD 19.4) and 44 patients (77.2%) were male. Eleven patients (19.3%) required massive transfusion (MT), 5 patients died in ED (8.8%) and overall in-hospital mortality was 22.8% (n = 13). Median time from admission to CCT result was 83 minutes (IQR 60–93) compared to 51 minutes (IQR 32-93; p = 0.0006) for ROTEM A5 results. This time difference was present for both MT and non-MT patients. Trauma-induced coagulopathy (TIC) was identified in 14 (24.5%) patients using CCT compared to 22 (38.5%) using ROTEM (p = 0.11 ns). Conclusion: Our ROTEM Sigma based algorithm enables a coagulation result to be obtained faster than laboratory CCT and could lead to earlier clinical intervention
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