Point-of-Care diagnostics of coagulation in the management of bleeding and transfusion in trauma patients

A Deployable Viscoelastic Coagulation Monitor Enables Point-of-Care Assessment of Coagulopathy in Swine With Polytrauma

INTRODUCTION

Absence of pre-hospital coagulation tests challenges prompt management of hemostasis after trauma. The Viscoelastic Coagulation Monitor (VCM, Entegrion, Durham, NC) is a hand-held coagulation test for point-of-care. We evaluated VCM in a translational swine polytrauma model, hypothesizing that VCM correlates with a laboratory reference method, the TEG 5000 (Haemonetics, Boston, MA), and can identify coagulopathic phenotypes relevant to trauma. Our secondary hypothesis was that pre-warming of VCM disposable test cartridges using a heating plate versus pre-warming of cartridges by carrying the cartridge in the user's pocket does not significantly alter results.

MATERIALS AND METHODS

This study was conducted in tandem with a parent study involving anesthetized, mechanically ventilated swine (n = 20; 54 ± 5 kg) that encountered traumatic brain injury, pulmonary contusion and hemorrhage, or combination/polytrauma injury. Blood was collected at baseline, post-injury, post-shock, post-transfusion, and 6-, 24-, and 48 h post-injury to perform VCM at point-of-care. Within-group effect of time was assessed. Spearman correlation examined linear relations between VCM and standard laboratory-based coagulation tests; as well as lactate, ionized calcium, and body temperature. Logistic regression examined predictiveness of VCM to identify coagulopathic phenotypes, with receiver operator characteristic curves generated to assess diagnostic capability. At a subset of timepoints, necessity of pre-warming the VCM test cartridge using a heating plate versus pre-warming the cartridge by placement in the user's pocket was assessed by conducting simultaneous tests on two separate instruments, with results analyzed by paired t-test with crossover design.

RESULTS

VCM revealed time-dependent changes in clotting time, clot formation time (CFT), alpha, maximum clot firmness (MCF), and lysis index (LI30). All VCM metrics correlated with the respective TEG 5000 metrics, with strongest correlation for VCM MCF with TEG MA (rhos = 0.77, P < .0001) and VCM LI30 with TEG LY30 (rhos = -0.76, P < .0001). VCM demonstrated good (area under the curve >0.70) to excellent (area under the curve >0.90) diagnostic accuracy in detection of low platelet count (MCF), low hematocrit (clotting time, clot formation time, alpha, and MCF), low fibrinogen (MCF), and high fibrinogen (alpha, MCF). There was no statistically or clinically relevant effect of cartridge warming method on results.

CONCLUSIONS

In a trauma model, VCM detected significant changes in coagulation at point-of-care in a simplified portable form factor. VCM could enable informed hemostasis management in pre-hospital settings where coagulations tests are unavailable, pending further validation in clinical trials.

Multichannel resonant acoustic rheometry system for quantification of coagulation of multiple human plasma samples

Resonant Acoustic Rheometry (RAR), a newly developed ultrasound-based technique for non-contact characterization of soft viscoelastic materials, has shown promise for quantitative viscoelastic assessment of temporally changing soft biomaterials in real time, and may be used to monitor blood coagulation process. Here, we report the development of a novel, multichannel RAR (mRAR) system for simultaneous measurements of multiple temporally evolving samples and demonstration of its use for monitoring the coagulation of multiple small-volume plasma samples. The mRAR system was constructed using an array of 4 custom-designed ultrasound transducers at 5.0 MHz and a novel electronic driving system that controlled the generation of synchronized ultrasound pulses for real time assessment of multiple samples simultaneously. As a proof-of-concept of the operation of the mRAR system, we performed tests using pooled normal human plasma samples and anti-coagulated plasma samples from patients treated with warfarin with a range of International Normalized Ratio (INR) values as well-characterized samples with different coagulation kinetics. Our results show that simultaneous tracking of dynamic changes in 4 plasma samples triggered by either kaolin or tissue factor was achieved for the entire duration of coagulation. The mRAR system captured distinct changes in the samples and identified parameters including the clotting start time and parameters associated with the stiffness of the final clots that were consistent with INR levels. Data from this study demonstrate the feasibility of the mRAR system for efficient characterization of the kinetic coagulation processes of multiple plasma samples.

Is it possible to improve prediction of outcome and blood requirements in the severely injured patients by defining categories of coagulopathy?

PURPOSE

It has been suggested to define the Trauma-induced coagulopathy (TIC) with a PT_ratio threshold of 1.20. We hypothesized that a more pragmatic classification would grade severity according to the PT_ratio (or corresponding ROTEM clotting time: EXTEM-CT), and that this would correlate better with the need for blood products (BP) and prognosis.

METHODS

Retrospective analysis of prospectively collected data of 1076 severely injured patients admitted from 01/2011 to 12/2019 in a university hospital. To determine the number of TIC categories and the best PT_ratio or EXTEM-CT thresholds for mortality at 24-h, a modified Mazumdar approach was used. Multivariate regression analyses were done to describe the relationship between PT_ratio and ROTEM parameter subclasses with mortality.

RESULTS

Three thresholds were, respectively, identified for PT_ratio (1.20, 1.90 and 3.00) and EXTEM-CT (90 s, 130 s, 200 s). The following categories were defined for PT_ratio: ≤ 1.20 (No TIC), 1.21-1.90 (Moderate TIC), 1.91-3.00 (severe TIC), > 3.00 (major TIC); and for EXTEM-CT: < 91 s (no TIC), 91-130 s (moderate TIC), 131-200 s (severe TIC) and > 200 s (major TIC). We observed that when the PT_ratio (or EXTEM-CT) increased, mortality and BP requirements increased. After multiple adjustments, we observed that each subclass of PT_ratio and EXTEM-CT was independently associated with mortality at 24-h.

CONCLUSION

In this study, we have described a pragmatic classification of coagulopathy utilizing PT_ratio and EXTEM-CT where increasing severity was associated with prognosis and the amount of BP administered. This could allow clinicians to better predict the outcome and anticipate the need for blood products.

Clinical application of viscoelastic point-of-care tests of coagulation-shifting paradigms

Bleeding during cardiac surgery, liver transplant, trauma and post partum hemorrhage are often multifactorial and these factors are dynamic as new factors crop up during the course of management. Conventional tests of coagulation offer information of a part of the coagulation system and also is time consuming. Viscoelastic point of care tests (VE POCTs) like rotational thromboelastometry, thromboelastogram and Sonoclot, are based on analysis of the viscoelastic properties of clotting blood and provide information for the entire coagulation pathway. In this comprehensive review being presented here, we have examined the pros and cons of VE POCTs including clinical, cost and survival benefits. The recommendations of the various guidelines regarding use of VE POCTs in various scenarios have been discussed. The review also tried to offer suggestions as to their optimal role in management of bleeding during cardiac surgeries, extracorporeal membrane oxygenation, left ventricular assist devices, liver transplant and briefly in trauma and postpartum hemorrhage.

What's new in trauma 2020

Throughout the past 2020, the pandemic COVID-19 has caused a big global shock, meanwhile it brought a great impact on the public health network. Trauma emergency system faced a giant challenge and how to manage trauma under the pandemic of COVID-19 was widely discussed. However, the trauma treatment of special population (geriatric patients and patients taking anticoagulant drugs) has received inadequate attention. Due to the high mortality following severe traumatic hemorrhage, hemostasis and trauma-induced coagulopathy are the important concerns in trauma treatment. Sepsis is another topic should not be ignored when we talking about trauma. COVID-19 itself is a special kind of sepsis, and it may even be called as serious systemic infection syndrome. Sepsis has been become a serious problem waiting to be solved urgently no matter in the fields of trauma, or in intensive care and infection, etc. This article reviewed the research progress in areas including trauma emergency care, trauma bleeding and coagulation, geriatric trauma and basic research of trauma within 2020.