In Part 2 of ROTEM for Trauma: Blood is Thicker with Wine – we will review the approach to interpreting ROTEM and how it can guide massive transfusion in the injured and bleeding patient. We will also touch on the practical considerations for starting a ROTEM program at your centre. To review the evidence for ROTEM in trauma, please see Part 1, which can be found here.

Normal ROTEM

This is a normal ROTEM output. For the purposes of acute bleeding in trauma, we focus on EXTEM and use FIBTEM as required.

Normal ROTEM

We’ll present the approach to ROTEM in multiple formats (i.e. pictorial, flowchart, chart, an analogy to drinking glasses, algorithm, etc.)

  • The output shows the amplitude of the forming clot over time
  • The important variables for acute management of trauma are:
    • Clotting Time (CT) –time from test start to amplitude 2mm; initiation of clotting by clotting factors
    • α-angle – slope of tangent at 2mm; speed of fibrin accumulation (thrombin burst, propagation)
    • Maximum clot firmness (MCF) – maximum clot amplitude; dependent on fibrinogen and platelets
      • Now we can get fancy and talk about the clot formation time (CFT ) and A10
        • CFT – time from amplitude 2 to 20mm; amplification, mostly fibrinogen dependent
        • A10 – amplitude at 10min, surrogate for MCF (allows same guided approach without waiting the full test time for MCF)
      • Lysis index at 30mins (LI30) – % drop in amplitude from MCF at 30min; hyperfibrinolysis
    • Basically:
      • Increased clotting time (EXTEM) – clotting factor issue – give FFP/FDP
      • Decreased alpha angle or CFT – fibrinogen issue – cryoprecipitate/fibrinogen
      • Decreased MCF – platelets or fibrinogen – examine FIBTEM to determine which to give
      • Increased LI30 – Hyperfibrinolysis – give tranexamic acid

Approach to ROTEM

The approach below was originally posted by EMRA and is focused on 3 simple questions: (1) how fast, (2) how strong, and (3) for how long?

  • How fast?
    • Initiation phase: Clotting factor dependent
    • CT on EXTEM – FFP/FDP, PCC
  • How strong?
    • Fibrin and platelet dependent
    • MCF on EXTEM and FIBTEM
      • MCF represents overall stability of clot (platelets 80%, fibrin 20% interacting via GPIIb/IIIa)
      • If abnormal, must assess fibrin and platelet contribution separately
        • If FIBTEM abnormal – replace fibrinogen (fibrinogen or cryo)
        • If MCF abnormal but FIBTEM normal – replace platelet
        • If BOTH abnormal – treat and repeat test; whenever you replace one, run test again to detect if deficiency in other
      • For how long?
        • Fibrinolysis
        • Overactive Plasmin causes hyperfibrinolysis
        • Lysis at 30min and 60min – (LY30, LY60) – TXA

Approach to ROTEM

Let’s look at the approach in tabular format:

Approach to ROTEM

That brings us to likely the most famous of interpretation techniques – the comparison of ROTEM/TEG outputs to drinking glasses:

Approach to ROTEM

Below is a Canadian transfusion algorithm currently in use based on ROTEM:

ROTEM algorithm

The Implementation of ROTEM

  • Establishing ROTEM/TEG at any centre will require champions and a Working Group with support and leadership from Laboratory medicine, Trauma, Anesthesia, ICU, Emergency Medicine
  • The centre will then have to decide if the test will be performed at the bedside or centrally:
    • Point-of-care would have:
    • Faster turnaround time (no transport)
    • BUT:
      • Multiple analyzers needed in multiple areas
      • Requires dedicated staff in multiple areas (taken away from active patient care)
      • No automated entry of results
      • No QA/QC protocols unless oversight from lab
    • Lab-based
      • QA and accreditation standards maintained
      • Standardized users, no need to train staff in multiple clinical areas (prevents mistakes from inappropriate use)
      • Increased involvement of hematopathologists and transfusion medicine specialists
      • BUT:
        • Requires good communication b/w care areas and lab for fast turnaround time
        • Specimen transport can take 5-10min
        • Well-established/reliable transport mechanisms required
      • In the several Canadian centers that utilize ROTEM, the ROTEM device is centrally located and lab-run
        • Samples are taken in the various clinical care areas – which are transported by porter or pneumatic tube to the lab for rapid turnaround. These samples are processed centrally, and a live output of the test is available at any computer terminal via ROTEM Connect.

ROTEM implementation

The Main Barrier to Implementation: Cost

  • A consensus conference of the US JTACS stated:
    • The costs of starting a program have been found to range from 100,000 to 125,000 USD. Though in the US, the ongoing costs are comparable to those of other conventional coagulation tests
    • Cost-effectiveness has been demonstrated in the non-trauma setting and is in large part caused by the decrease in the consumption of blood products, which may result from improved hemostatic management
  • Two systematic reviews have looked at the issue of cost-effectiveness:
    • Holcomb and colleagues examined 1974 consecutive patients with trauma comparing rTEG with CCTs in 2012.
      • Found that the cost of rTEG ($317) was not excessive compared with the CCTs ($286) on the basis that rTEG was available long before CCT results.
      • They concluded that rTEG could replace CCTs entirely.
    • Whiting et al, in 2015, looked at the clinical effectiveness and cost-effectiveness of VE devices in cardiac surgery, trauma-induced coagulopathy, and PPH.
      • For the trauma population, the cost-savings owing to VE testing were more substantial, amounting to per-patient savings of £688 for ROTEM compared with SLTs, £721 for TEG, and £818 for Sonoclot. This finding was entirely dependent on material costs, which are slightly higher for ROTEM. The increased savings were due to the higher volume of blood products transfused in trauma patients. VE testing remained cost-saving following various scenario analyses.
      • This conclusion is predicated on the assumption that viscoelastic testing leads to improved clinical outcomes in the trauma population, which again could not be established from existing studies, and in the absence of convincing data, the cost-savings remain more theoretical.
      • The per-patient cost-savings were £43 for ROTEM, £79 for TEG, and £132 for Sonoclot, as a result of the cost of purchasing each base viscoelastic system, with the basic ROTEM system being most expensive, and Sonoclot the least expensive
    • The difference in the Canadian system is that hospital’s themselves do not pay for blood products, they are provided by the Canadian Blood Services – so these cost-savings would be seen on a SYSTEMS-WIDE level and not a per hospital level.
    • That being what it is, the potential benefit to the system from decreased blood product usage, the decreased transfusion risk to the patient, the ability to tailor hemostatic resuscitation, and the growing evidence of possible mortality benefit make ROTEM an attractive option.

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Richard Hoang

Richard Hoang

Dr. Richard Hoang is a 5th year Emergency Medicine Resident at the University of Ottawa with a variety of academic interests including military medicine, trauma, simulation, and FOAMed.