Validation of the time to attain maximal clot amplitude after reaching maximal clot formation velocity parameter as a measure of fibrinolysis using rotational thromboelastometry and its application in the assessment of fibrinolytic resistance in septic patients: a prospective observational study: communication from the ISTH SSC Subcommittee on Fibrinolysis

BACKGROUND

In sepsis, fibrinolysis resistance correlates with worse outcomes. Practically, rotational thromboelastometry (ROTEM) is used to report residual clot amplitude relative to maximum amplitude at specified times after clot formation clot lysis indices (CLIs). However, healthy individuals can exhibit similar CLIs, thus making it challenging to solely diagnose the low fibrinolytic state. Furthermore, CLI does not include the kinetics of clot formation, which can affect overall fibrinolysis. Therefore, a more nuanced analysis, such as time to attain maximal clot amplitude after reaching maximal clot formation velocity (t-AUCi), is needed to better identify fibrinolysis resistance in sepsis.

OBJECTIVES

To evaluate the correlation between the degree of fibrinolytic activation and t-AUCi in healthy or septic individuals.

METHODS

Whole blood (n = 60) from septic or healthy donors was analyzed using tissue factor-activated (EXTEM) and nonactivated (NATEM) ROTEM assays. Lysis was initiated with tissue-type plasminogen activator, and CLI and t-AUCi were calculated. Standard coagulation tests and plasma fibrinolysis markers (D-dimer, plasmin-α2-antiplasmin complex, plasminogen activator inhibitor type 1, and plasminogen) were also measured.

RESULTS

t-AUCi values decreased with increasing fibrinolytic activity and correlated positively with CLI for different degrees of clot lysis both in EXTEM and NATEM. t-AUCi cutoff value of 1962.0 seconds in EXTEM predicted low fibrinolytic activity with 81.8% sensitivity and 83.7% specificity. In addition, t-AUCi is not influenced by clot retraction.

CONCLUSION

Whole-blood point-of-care ROTEM analyses with t-AUCi offers a more rapid and parametric evaluation of fibrinolytic potential compared with CLI, which can be used for a more rapid and accurate diagnosis of fibrinolysis resistance in sepsis.

Pneumatic tube transport of blood samples affects global hemostasis and platelet function assays

INTRODUCTION

Pneumatic tube systems (PTS) are frequently used for rapid and cost-effective transportation of blood samples to the clinical laboratory. The impact of PTS transport on platelet function measured by the Multiplate system and global hemostasis measured by the TEG 5000 was evaluated.

METHODS

Paired samples from healthy adult individuals were obtained at two study sites: Rigshospitalet (RH) and Nordsjaellands Hospital (NOH). One sample was transported by PTS and one manually (non-PTS). Platelet function was assessed by platelet aggregation (Multiplate) and global hemostasis was assessed by a variety of thrombelastography (TEG) assays. Multiplate (n = 39) and TEG (n = 32) analysis was performed at site RH, and Multiplate (n = 28) analysis was performed at site NOH.

RESULTS

A significant higher agonist-induced platelet aggregation was found for PTS samples compared to manual transport at site NOH (P < .02, all agonists). No significant difference was found at site RH (P > .05, all agonists). For Kaolin TEG, samples transported by PTS showed a significant lower R-time and higher Angle (P < .001). No significant differences in MA and LY30 was found (P > .05). ACT of RapidTEG was significantly reduced (P = .001) and MA of Functional Fibrinogen TEG was significantly increased (P < .001) after PTS transport. No significant impact of PTS was observed for TEG assays with heparinase (P > .05).

CONCLUSIONS

Depending on the type of PTS, transportation by PTS affected platelet aggregation measured by Multiplate. Furthermore, PTS alters TEG parameters possibly reflecting coagulation factors. Clinical laboratories should evaluate the effect of the local PTS on Multiplate and TEG results.

The Modern Pneumatic Tube System Transports with Reduced Speed Does Not Affect Special Coagulation Tests

Pneumatic tube transport systems (PTS) for delivery of patient samples to a hemostasis laboratory are often used to reduce turnaround time for vital analyses. PTS in our hospital has the ability to regulate the transport speed in the range of 3-6 m/s with acceleration control technology. We evaluated the effects of PTS transport for routine coagulation tests, platelet function tests and special global coagulation tests. Duplicate samples were collected from 29 patients and 40 healthy individuals. One sample was sent using PTS and the other was carried by personnel to the lab for determination of protrombin time, activated partial thromboplastin time, trombin time, fibrinogen, antitrombin and thrombin generation test. Platelet function was measured by means of a Apact 4004® analyzer using the inductors (ADP, Arachidonic acid and Epinephrine). Samples transported using PTS with normal transport speed 6 m/s does not affect basic coagulation tests (PT, aPTT, FIB, TT and AT), but TGT has significantly altered. The use of PTS with controlled acceleration regulated the increase in thrombin generation from 10% to 3%, which is not statistically signifiant. The use of PTS with controlled acceleration did not show a significant difference even with the highly sensitive method of platelet aggregation. We conclude that PTS with acceleration control with transport speed from 3 to 6 m/s does not affect to platelet activity as measured by LTA and also global coagulation test - TGT. The advantage of PTS transport is very rapid assessment laboratory testing. From the above validation study, it is clear that PTS should always be validated for specialized laboratory methods and appropriately adapted to specific transport conditions.

Viscoelastic haemostatic assays in aeromedical transport

OBJECTIVE

To assess the feasibility of using rotational thromboelastometry (ROTEM®)-sigma and thromboelastography (TEG®)-6s viscoelastic point-of-care assays during rotary wing aeromedical transport, and to determine the reliability of the results obtained.

METHODS

A single centre, prospective, observational, non-interventional feasibility study performed at Gold Coast University Hospital intensive care unit, and in a LifeFlight Retrieval Medicine operated Leonardo AW139 helicopter. Blood was collected from eight healthy volunteers on 18 April 2019 and all testing was performed on that day. Functions measured were ROTEM-sigma extrinsically activated thromboelastometry (EXTEM) clotting time (CT), EXTEM amplitude at 5 min after CT (A5) and fibrin-based extrinsically activated thromboelastometry (FIBTEM) A5, and TEG-6s Kaolin (CK) reaction time (R), functional fibrinogen (CFF) maximal amplitude (MA) and CFF amplitude at 10 min after R (A10). Differences between the results obtained in the helicopter and control results at Gold Coast University Hospital during flight and after flight, and also differences in control results over time up to 3 h were analysed.

RESULTS

During flight both the ROTEM-sigma and TEG-6s devices failed to give reliable results. Post flight, the helicopter and control samples correlated well. Repeat testing of control samples at 1 and 3 h also revealed good correlation over time.

CONCLUSION

It is feasible to reliably run tests on both the ROTEM-sigma and TEG-6s after the devices have been flown in a rotary wing aircraft. However, testing cannot be performed while in flight conditions. It is also possible to run blood samples collected up to 3 h prior and acquire results which correlate well with initial testing.

Alterations in the parameters of classic, global, and innovative assays of hemostasis caused by sample transportation via pneumatic tube system

BACKGROUND

Pneumatic tube system (PTS) is an integral part of large medical facilities providing rapid interconnection between units within the hospital and often used to transport blood samples. The aim of our study was to compare a wide variety of hemostasis assays to identify assays sensitive to this transport method and diagnostic relevance of the alterations.

METHODS

Routine coagulation and platelet tests (APTT, PT, TT, fibrinogen, light transmission aggregometry (LTA) with ADP, collagen, ristomycin and epinephrine), whole blood flow cytometry platelet function test (levels of CD42b, CD61, CD62P, PAC1, annexin V binding and mepacrine release) and global coagulation tests (thromboelastography (TEG), thrombin generation (TGT), thrombodynamics (TD), thrombodynamics-4D (TD-4D)) were determined in PTS- and manually transported samples of 10 healthy volunteers.

RESULTS

There were no significant differences between the values of APTT, PT, TT or fibrinogen between the samples transported by PTS or manually. The results for LTA demonstrated increase in the collagen-induced aggregation (84 ± 7% versus 73 ± 5%), while the response to epinephrine was decreased (58 ± 20% versus 72 ± 7.4%). Flow cytometry-based platelet function test showed a pre-activation of platelets by PTS-transportation while all integral assays of coagulation tested in the present study (TEG, TGT, TD, TD-4D) demonstrated a hypercoagulation shift.

CONCLUSIONS

Transportation by PTS caused significant shifts in parameters of functional and integral assays that exceeded parameter variation values and sometimes even were comparable to normal ranges. The results obtained in this study indicate that using of PTS for such assays may cause sufficient alterations of results and can lead to patient's mistreatment.

Blood Sample Transportation by Pneumatic Transportation Systems: A Systematic Literature Review

BACKGROUND

Pneumatic transportation systems (PTSs) are increasingly used for transportation of blood samples to the core laboratory. Many studies have investigated the impact of these systems on different types of analyses, but to elucidate whether PTSs in general are safe for transportation of blood samples, existing literature on the subject was systematically assessed.

METHODS

A systematic literature review was conducted following the preferred reporting items for systematic reviews and metaanalyses (PRISMA) Statement guidelines to gather studies investigating the impact of PTS on analyses in blood samples. Studies were extracted from PubMed and Embase. The search period ended November 2016.

RESULTS

A total of 39 studies were retrieved. Of these, only 12 studies were conducted on inpatients, mainly intensive care unit patients. Blood gases, hematology, and clinical chemistry were well investigated, whereas coagulation, rotational thromboelastometry, and platelet function in acutely ill patients were addressed by only 1 study each. Only a few parameters were affected in a clinically significant way (clotting time parameter in extrinsic system thromboelastometry, pO2 in blood gas, multiplate analysis, and the hemolysis index).

CONCLUSIONS

Owing to their high degree of heterogeneity, the retrieved studies were unable to supply evidence for the safety of using PTSs for blood sample transportation. In consequence, laboratories need to measure and document the actual acceleration forces in their existing PTS, instituting quality target thresholds for these measurements such as acceleration vector sums. Computer modeling might be applied to the evaluation of future PTS installations. With the increasing use of PTS, a harmonized, international recommendation on this topic is warranted.

Correlation between laboratory coagulation testing and thromboelastometry is modified during management of trauma patients

BACKGROUND

Thromboelastometry (ROTEM, Pentapharm GmbH, Munich, Germany) is increasingly being used to make a diagnosis of coagulopathy and to guide hemostatic therapy (HT). Although ROTEM parameters and standard laboratory test (SLT) correlated well before administration of HT, it is not known if this correlation persists after hemostatic resuscitation.

METHODS

A retrospective analysis of prospectively collected data from a trauma registry (2011-2014) was performed. All patients having a ROTEM analysis were included. ROTEM parameters (clotting time and clot amplitude at 5 minutes) were determined after activation with tissue factor (EXTEM) or platelet inhibition with cytochalasin D (FIBTEM). Spearman rank correlation coefficient was calculated for the correlation between SLT and thromboelastometry parameters, and thresholds were determined with receiver operating characteristic (ROC) curve analysis for the diagnosis of an international normalized ratio (INR) greater than 1.5, fibrinogen 1.5 g/L or less, and platelet count of less than 100.10/L.

RESULTS

Of the 358 patients included, 533 thromboelastometry results were obtained (335 at admission, 198 during care). Correlation between INR and EXTEM-clotting time was good at admission (r = 0.617) in the whole cohort but decreased in the subgroup of patients having an Injury Severity Score of less than 25 (r = 0.399) or a base excess of less than 6 mmol/L (r = 0.489). During care, correlation was impaired after the administration of fibrinogen concentrates in the whole cohort (r = 0.430), as well as in the subgroup of patients having an Injury Severity Score greater than 24 (r = 0.465). As well, for the diagnosis of increased INR, sensitivity and the area under the ROC curve decreased from 75% and 0.894 (no treatment) to 20% and 0.653 (fibrinogen concentrate). Areas under the ROC curve for the prediction of a fibrinogen or platelet decrease were not significantly altered regardless of the treatment group.

CONCLUSIONS

A decrease in the correlation between SLTs and ROTEM parameters was observed at admission or during care, which could be in relation with injury severity, base deficit, or the administration of blood products, particularly fibrinogen concentrate. Further work will be necessary to better understand which tool is the most suitable for guiding HT.

LEVEL OF EVIDENCE

Therapeutic study, level IV; diagnostic study, level IV.

Comparison of citrated and fresh whole blood for viscoelastic coagulation testing during elective neurosurgery

BACKGROUND

Previous viscoelastic haemostatic tests studies have often indicated a hypercoagulative test signal with citrated blood, which could influence clinical decision makings.

PURPOSE

The aim of this study was to compare fresh and citrated whole blood using two non-automated viscoelastic ROTEM and Sonoclot tests. Our hypothesis was that citrated blood would demonstrate a hypercoagulative response in this setting, not tested before.

METHODS

Perioperative viscoelastic coagulation changes were evaluated with a ROTEM and Sonoclot in 38 patients undergoing elective brain tumor surgery. The citrated samples were recalcified with CaCl₂. Wilcoxon nonparametric-paired tests and Bland-Altman plots were performed to compare the fresh and citrated blood analyses.

RESULTS

The citrated blood showed a hypercoagulative response in ROTEM NATEM-clot formation time and α-angle, Sonoclot-clot rate and platelet function, as compared to fresh blood (p<0.0001).

CONCLUSIONS

Fresh whole blood may theoretically reflect in vivo haemostasis more closely than citrated analyses, which indicated a hypercoagulative response as compared to the fresh whole blood analyses Bland-Altman plots also indicated that ROTEM reference ranges in patients undergoing brain surgery should be redefined. Future studies must establish the correlation between viscoelastic test results using fresh or citrate anticoagulated blood and clinical outcomes, such as bleeding, transfusion or reoperation for postoperative haematoma.

Can we rely on out-of-hospital blood samples? A prospective interventional study on the pre-analytical stability of blood samples under prehospital emergency medicine conditions

Background

Prehospital intravenous access provides the opportunity to sample blood from an emergency patient at the earliest possible moment in the course of acute illness and in a state prior to therapeutic interventions. Our study investigates the pre-analytical stability of biomarkers in prehospital emergency medicine and will answer the question whether an approach of blood sampling out in the field will deliver valid laboratory results.

Methods

We prepared pairs of blood samples from healthy volunteers and volunteering patients post cardio-thoracic surgery. While one sample set was analysed immediately, the other one was subjected to a worse-than-reality treatment of 60 min time-lapse and standardized mechanical forces outside of the hospital through actual ambulance transport. We investigated 21 parameters comprising blood cells, coagulation tests, electrolytes, markers of haemolysis and markers of cardiac ischemia. Bland-Altman analysis was used to investigate differences between test groups. Differences between test groups were set against the official margins of test accuracy as given by the German Requirements for Quality Assurance of Medical Laboratory Examinations.

Results

Agreement between immediate analysis and our prehospital treatment is high as demonstrated by Bland-Altman plotting. Mechanical stress and time delay do not produce a systematic bias but only random inaccuracy. The limits of agreement for the tested parameters are generally within clinically acceptable ranges of variation and within the official margins as set by the German Requirements for Quality Assurance of Medical Laboratory Examinations.

Discussion

We subjected blood samples to a standardized treatment marking a worse-than-reality scenario of prehospital time delay and transport. Biomarkers including indicators of myocardial ischemia showed high pre-analytical stability.

Conclusion

We conclude the validity of blood samples from a prehospital environment.

Electronic supplementary material

The online version of this article (doi:10.1186/s13049-017-0371-3) contains supplementary material, which is available to authorized users.

Can rotational thromboelastometry predict septic disseminated intravascular coagulation?

Rotational thromboelastometry (ROTEM), known as point-of-care testing, has been incorporated into various kinds of postsurgical management. However, the utility of ROTEM for rapid diagnosis of sepsis-induced disseminated intravascular coagulation (DIC) has not been investigated. This retrospective study includes 13 sepsis patients who underwent ROTEM in our emergency department in 2013. All patients were divided into two groups on the basis of the presence of DIC diagnosed by the Japanese Association for Acute Medicine (JAAM) DIC score. We evaluated the demographics, clinical characteristics, laboratory data, ROTEM test and outcomes for each patient. The correlations between JAAM DIC score and significantly different parameters by univariate analysis and receiver operating characteristic (ROC) analysis were performed to assess the accuracy of the variables. There were seven and six patients in the DIC group and non-DIC group, respectively. The DIC group showed significantly longer prothrombin times, international normalized ratio of prothrombin time and clotting times (CTs) in the EXTEM test, and higher fibrinogen and fibrin degradation products and D-dimer. The CT in EXTEM test was correlated more with JAAM DIC score (r = 0.798), than the standard coagulation test. These parameters were accurate predictors in the diagnosis of septic DIC, with an AUC of 0.952, and a cut-off value of more than 46.0 s, resulting in a sensitivity of 100.0% and a specificity of 83.3%. CT in the EXTEM test was a single reliable indicator of sepsis-induced DIC diagnosed by the JAAM DIC score, and strongly associated with severity of DIC.

[Early viscoelasticity-based coagulation therapy for severely injured bleeding patients: Report of the consensus group on the consensus conference 2014 for formulation of S2k guidelines]

Although there is increasing interest in the use of a viscoelastic test procedure (ROTEM/TEG) for diagnostics and therapy guidance of severely injured and bleeding patients, currently no uniformly accepted guidelines exist for how this technology should be integrated into clinical treatment. In September 2014 an international multidisciplinary group of opinion leaders in the field of trauma-induced coagulopathy and other disciplines involved in the treatment of severely injured patients were assembled for a 2-day consensus conference in Philadelphia (USA). This panel included trauma/accident surgeons, general/abdominal surgeons, vascular surgeons, emergency/intensive care surgeons, hematologists, transfusion specialists, anesthesiologists, laboratory physicians, pathobiologists/pathophysiologists and the lay public. A total of nine questions regarding the impact of viscoelastic testing in the early treatment of trauma patients were developed prior to the conference by a panel consensus. Early use was defined as baseline viscoelastic test result thresholds obtained within the first minutes of hospital arrival, when conventional laboratory results are not yet available. The available data for each question were then reviewed in person using standardized presentations by the expert panel. A consensus summary document was then developed and reviewed by the panel in an open forum. Finally, a 2-round Delphi poll was administered to the panel of experts regarding viscoelastic thresholds for triggering the initiation of specific treatments including fibrinogen (concentrates), platelet concentrates, blood plasma products and prothrombin complex concentrates (PCC). This report summarizes the findings and recommendations of this consensus conference, which correspond to a S2k guideline according to the system of the Association of the Scientific Medical Societies in Germany (AWMF) and taking formal consensus findings including Delphi methods into consideration.

2014 Consensus conference on viscoelastic test-based transfusion guidelines for early trauma resuscitation: Report of the panel

There has been an increased interest in the use of viscoelastic testing to guide blood product replacement during the acute resuscitation of the injured patient. Currently, no uniformly accepted guidelines exist for how this technology should be integrated into clinical care. In September 2014, an international multidisciplinary group of leaders in the field of trauma coagulopathy and resuscitation was assembled for a 2-day consensus conference in Philadelphia, Pennsylvania. This panel included trauma surgeons, hematologists, blood bank specialists, anesthesiologists, and the lay public.Nine questions regarding the impact of viscoelastic testing in the early resuscitation of trauma patients were developed before the conference by panel consensus. Early use was defined as baseline viscoelastic test result thresholds obtained within the first minutes of hospital arrival-when conventional laboratory results are not available. The available data for each question were then reviewed in person using standardized presentations by the expert panel. A consensus summary document was then developed and reviewed by the panel in an open forum. Finally, a two-round Delphi poll was administered to the panel of experts regarding viscoelastic thresholds for triggering the initiation of specific treatments including fibrinogen, platelets, plasma, and prothrombin complex concentrates. This report summarizes the findings and recommendations of this consensus conference.

NT-proBNP on Cobas h 232 in point-of-care testing: Performance in the primary health care versus in the hospital laboratory

BACKGROUND

NT-proBNP may be useful for ruling out heart failure in primary health care. In this study we examined the analytical quality of NT-proBNP in primary health care on the Cobas h 232 point-of-care instrument compared with measurements performed in a hospital laboratory.

MATERIALS AND METHODS

Blood samples requested for NT-proBNP were collected in primary health care (n = 95) and in a hospital laboratory (n = 107). NT-proBNP was measured on-site on Cobas h 232 instruments both in primary health care centres and at the hospital laboratory and all samples were also analyzed with a comparison method at the hospital. Precision, trueness, accuracy, and lot-variation were determined at different concentration levels and evaluated according to acceptance criteria. Furthermore user-friendliness was assessed by questionnaires.

RESULTS

For Cobas h 232 repeatability CV was 8.5-10.7% in the hospital setting and 5.3-10.0% in the primary health care and within the analytical quality specifications, but higher than with the comparison method (< 4%). NT-proBNP results obtained in primary health care were significantly higher than by the hospital comparison method (bias ranged from 14.3-23.7%), whereas there was no significant bias when Cobas h 232 was used in the hospital setting (bias ranged from - 4.9 to 7.0%). User-friendliness of Cobas h 232 was overall acceptable.

CONCLUSION

Cobas h 232 point-of-care instrument for measurement of NT-proBNP performed satisfactorily with regard to precision, user-friendliness, and lot-variation. A decrease in NT-proBNP levels observed in samples transported to a central laboratory needs further attention and investigation.